[clang] Refactor clang's keyword enable/disable mechanism to allow lldb to re-use it#165323

dsandersllvm merged 4 commits intollvm:mainllvm/llvm-project:mainfrom

dsandersllvm:lldb-parse-identifiers-keywords-clang-onlydsandersllvm/llvm-project:lldb-parse-identifiers-keywords-clang-onlyCopy head branch name to clipboard