[clang] [clang-format] Add support for absl nullability macros (PR #130346)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `arc-builder` running on `arc-worker` while building `clang` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/3/builds/13089

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

```
Step 6 (test-build-unified-tree-check-all) failure: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
...
8.071 [54/18/9] Linking CXX executable tools/clang/unittests/ASTMatchers/ASTMatchersTests
8.117 [53/18/10] Linking CXX executable tools/lld/unittests/AsLibELF/LLDAsLibELFTests
8.217 [52/18/11] Linking CXX executable tools/clang/unittests/Analysis/FlowSensitive/ClangAnalysisFlowSensitiveTests
8.286 [51/18/12] Linking CXX executable tools/clang/unittests/libclang/CrashTests/libclangCrashTests
8.474 [50/18/13] Linking CXX executable tools/clang/unittests/InstallAPI/InstallAPITests
8.613 [49/18/14] Linking CXX executable tools/clang/unittests/StaticAnalyzer/StaticAnalysisTests
8.804 [48/18/15] Preparing lit tests
9.089 [47/18/16] Linking CXX executable tools/lld/unittests/AsLibAll/LLDAsLibAllTests
9.842 [46/18/17] Linking CXX executable tools/clang/unittests/AST/ASTTests
10.356 [45/18/18] Linking CXX executable unittests/CGData/CGDataTests
command timed out: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1211.101355

```

</details>

https://github.com/llvm/llvm-project/pull/130346