[clang] [Format] Fix isStartOfName to recognize attributes (PR #76804)

[kadir çetinkaya via cfe-commits]

https://github.com/kadircet approved this pull request.

can you also add a test to clang/unittests/Format/TokenAnnotatorTest.cpp that ensures trailing attribute-like macros receive `StartOfName` annotation to make sure we don't regress the signal in the future?

https://github.com/llvm/llvm-project/pull/76804