[clang] [clang][test] add testing for the AST matcher reference (PR #94248)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `openmp-offload-libc-amdgpu-runtime` running on `omp-vega20-1` while building `clang` at step 7 "Add check check-clang".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/73/builds/6253

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (Add check check-clang) failure: test (failure)
...
[57/301] Building CXX object tools/clang/unittests/Analysis/CMakeFiles/ClangAnalysisTests.dir/CFGTest.cpp.o
[58/301] Building CXX object tools/clang/unittests/Analysis/CMakeFiles/ClangAnalysisTests.dir/CFGDominatorTree.cpp.o
[59/301] Building CXX object tools/clang/unittests/StaticAnalyzer/CMakeFiles/StaticAnalysisTests.dir/SValTest.cpp.o
[60/301] Building CXX object tools/clang/unittests/StaticAnalyzer/CMakeFiles/StaticAnalysisTests.dir/Z3CrosscheckOracleTest.cpp.o
[61/301] Building CXX object tools/clang/unittests/StaticAnalyzer/CMakeFiles/StaticAnalysisTests.dir/TestReturnValueUnderConstruction.cpp.o
[62/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/DebugSupportTest.cpp.o
[63/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/DeterminismTest.cpp.o
[64/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/CFGMatchSwitchTest.cpp.o
[65/301] Building CXX object tools/clang/unittests/StaticAnalyzer/CMakeFiles/StaticAnalysisTests.dir/IsCLibraryFunctionTest.cpp.o
[66/301] Generating ASTMatchersDocTests.cpp
FAILED: tools/clang/unittests/ASTMatchers/ASTMatchersDocTests.cpp /home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/tools/clang/unittests/ASTMatchers/ASTMatchersDocTests.cpp 
cd /home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/tools/clang/unittests/ASTMatchers && /home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.src/clang/utils/generate_ast_matcher_doc_tests.py --input-file /home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.src/clang/include/clang/ASTMatchers/ASTMatchers.h --output-file /home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.build/tools/clang/unittests/ASTMatchers/ASTMatchersDocTests.cpp
Traceback (most recent call last):
  File "/home/ompworker/bbot/openmp-offload-libc-amdgpu-runtime/llvm.src/clang/utils/generate_ast_matcher_doc_tests.py", line 94, in <module>
    statistics = defaultdict[str, int](int)
TypeError: 'type' object is not subscriptable
[67/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/RecordOpsTest.cpp.o
[68/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/MatchSwitchTest.cpp.o
[69/301] Building CXX object tools/clang/unittests/StaticAnalyzer/CMakeFiles/StaticAnalysisTests.dir/BugReportInterestingnessTest.cpp.o
[70/301] Building CXX object tools/clang/unittests/StaticAnalyzer/CMakeFiles/StaticAnalysisTests.dir/FalsePositiveRefutationBRVisitorTest.cpp.o
[71/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/ASTOpsTest.cpp.o
[72/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/SimplifyConstraintsTest.cpp.o
[73/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/LoggerTest.cpp.o
[74/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/TransferBranchTest.cpp.o
[75/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/TestingSupport.cpp.o
[76/301] Building CXX object tools/clang/unittests/Analysis/CMakeFiles/ClangAnalysisTests.dir/IntervalPartitionTest.cpp.o
[77/301] Building CXX object tools/clang/unittests/StaticAnalyzer/CMakeFiles/StaticAnalysisTests.dir/CallDescriptionTest.cpp.o
[78/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/ChromiumCheckModelTest.cpp.o
[79/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/TestingSupportTest.cpp.o
[80/301] Building CXX object tools/clang/unittests/Analysis/CMakeFiles/ClangAnalysisTests.dir/ExprMutationAnalyzerTest.cpp.o
[81/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/DataflowEnvironmentTest.cpp.o
[82/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/WatchedLiteralsSolverTest.cpp.o
[83/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/SignAnalysisTest.cpp.o
[84/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/SingleVarConstantPropagationTest.cpp.o
[85/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/MultiVarConstantPropagationTest.cpp.o
[86/301] Building CXX object tools/clang/unittests/StaticAnalyzer/CMakeFiles/StaticAnalysisTests.dir/ParamRegionTest.cpp.o
[87/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/UncheckedOptionalAccessModelTest.cpp.o
[88/301] Building CXX object tools/clang/unittests/StaticAnalyzer/CMakeFiles/StaticAnalysisTests.dir/StoreTest.cpp.o
[89/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/TypeErasedDataflowAnalysisTest.cpp.o
[90/301] Building CXX object tools/clang/unittests/AST/CMakeFiles/ASTTests.dir/ASTExprTest.cpp.o
[91/301] Building CXX object tools/clang/unittests/StaticAnalyzer/CMakeFiles/StaticAnalysisTests.dir/SymbolReaperTest.cpp.o
[92/301] Building CXX object tools/clang/unittests/ASTMatchers/Dynamic/CMakeFiles/DynamicASTMatchersTests.dir/RegistryTest.cpp.o
[93/301] Building CXX object tools/clang/unittests/AST/CMakeFiles/ASTTests.dir/ASTDumperTest.cpp.o
[94/301] Building CXX object tools/clang/unittests/ASTMatchers/Dynamic/CMakeFiles/DynamicASTMatchersTests.dir/VariantValueTest.cpp.o
[95/301] Building CXX object tools/clang/unittests/AST/CMakeFiles/ASTTests.dir/ASTContextParentMapTest.cpp.o
[96/301] Building CXX object tools/clang/unittests/ASTMatchers/Dynamic/CMakeFiles/DynamicASTMatchersTests.dir/ParserTest.cpp.o
[97/301] Building CXX object tools/clang/unittests/Analysis/FlowSensitive/CMakeFiles/ClangAnalysisFlowSensitiveTests.dir/TransferTest.cpp.o
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/94248