[clang] [clang-format] Add option to remove leading blank lines (PR #91221)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-x86_64-debian-fast` running on `gribozavr4` while building `clang` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/56/builds/799

Here is the relevant piece of the build log for the reference:
```
Step 5 (build-unified-tree) failure: build (failure)
...
/b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/Sema/CodeCompleteConsumer.h:338:31: warning: '@class' command should not be used in a comment attached to a non-class declaration [-Wdocumentation]
    /// Code completion in a @class forward declaration.
                             ~^~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clangd/refactor/tweaks/SpecialMembers.cpp:12:
/b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/Sema/Sema.h:9291:14: warning: parameter 'Converted' not found in the function declaration [-Wdocumentation]
  /// \param Converted Will receive the converted, canonicalized template
             ^~~~~~~~~
3 warnings generated.
31.856 [494/61/5364] Linking CXX executable bin/clang-include-fixer
32.206 [494/60/5365] Building CXX object tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Format.cpp.o
FAILED: tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Format.cpp.o 
CCACHE_CPP2=yes CCACHE_HASHDIR=yes /usr/bin/ccache /usr/bin/clang++ -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/b/1/clang-x86_64-debian-fast/llvm.obj/tools/clang/tools/extra/clangd -I/b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clangd -I/b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clangd/../include-cleaner/include -I/b/1/clang-x86_64-debian-fast/llvm.obj/tools/clang/tools/extra/clangd/../clang-tidy -I/b/1/clang-x86_64-debian-fast/llvm.src/clang/include -I/b/1/clang-x86_64-debian-fast/llvm.obj/tools/clang/include -I/b/1/clang-x86_64-debian-fast/llvm.obj/include -I/b/1/clang-x86_64-debian-fast/llvm.src/llvm/include -I/b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/pseudo/lib/../include -std=c++11 -Wdocumentation -Wno-documentation-deprecated-sync -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -fno-common -Woverloaded-virtual -Wno-nested-anon-types -O3 -DNDEBUG  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -std=c++17 -MD -MT tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Format.cpp.o -MF tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Format.cpp.o.d -o tools/clang/tools/extra/clangd/CMakeFiles/obj.clangDaemon.dir/Format.cpp.o -c /b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clangd/Format.cpp
/b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clangd/Format.cpp:284:11: error: no member named 'KeepEmptyLinesAtTheStartOfBlocks' in 'clang::format::FormatStyle'
    Style.KeepEmptyLinesAtTheStartOfBlocks = true;
    ~~~~~ ^
1 error generated.
33.581 [494/59/5366] Building AMDGPUGenAsmWriter.inc...
34.741 [494/58/5367] Building CXX object tools/clang/tools/extra/clang-tidy/bugprone/CMakeFiles/obj.clangTidyBugproneModule.dir/BugproneTidyModule.cpp.o
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp:12:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clang-tidy/bugprone/../cppcoreguidelines/NarrowingConversionsCheck.h:12:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clang-tidy/bugprone/../cppcoreguidelines/../ClangTidyCheck.h:14:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/ASTMatchers/ASTMatchFinder.h:43:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/ASTMatchers/ASTMatchers.h:48:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/AST/ASTTypeTraits.h:19:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/AST/DeclCXX.h:22:
/b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/AST/Expr.h:5147:21: warning: '@endcode' command does not terminate a verbatim text block [-Wdocumentation]
  /// literal or an @encode?
                    ^~~~~~~
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp:83:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.h:14:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/Analysis/FlowSensitive/Models/UncheckedOptionalAccessModel.h:20:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h:29:
/b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.h:104:14: warning: parameter 'Stmt' not found in the function declaration [-Wdocumentation]
  /// @param Stmt The condition which is responsible for the split in the CFG.
             ^~~~
2 warnings generated.
34.823 [494/57/5368] Building CXX object tools/clang/tools/extra/clangd/refactor/tweaks/CMakeFiles/obj.clangDaemonTweaks.dir/DefineInline.cpp.o
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp:9:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clangd/AST.h:16:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang-tools-extra/clangd/Headers.h:19:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/Frontend/CompilerInstance.h:16:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/Frontend/CompilerInvocation.h:23:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/StaticAnalyzer/Core/AnalyzerOptions.h:17:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/Analysis/PathDiagnostic.h:17:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/Analysis/AnalysisDeclContext.h:22:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/Analysis/CFG.h:18:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/AST/ExprCXX.h:21:
In file included from /b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/AST/DeclCXX.h:22:
/b/1/clang-x86_64-debian-fast/llvm.src/clang/include/clang/AST/Expr.h:5147:21: warning: '@endcode' command does not terminate a verbatim text block [-Wdocumentation]

```

https://github.com/llvm/llvm-project/pull/91221