[clang-tidy] Export fixes from check_clang_tidy.py (#88186)

Makes it possible to export fixes from running llvm-lit on a clang-tidy
test. To enable, modify the RUN invocation directly in the test with the
new -export flag. llvm-lit will report the test passed and fixes can be
found in the file specified to the -export flag.

GitOrigin-RevId: fad37526a3ea7d669af621342968029085862281
2 files changed