[clang] [clang-tools-extra] [llvm] [OptTable] Store Info strings in the string table (PR #218845)

[Fangrui Song via cfe-commits]

MaskRay wrote:

[size-file](https://llvm-compile-time-tracker.com/compare_clang.php?from=aa46cfeb86c0943cd99a9f4d00625ea3df509fe5&to=5cbe94a17858f9bf6ec6aa224671293fb6fd12b7&stat=size-file)	136835KiB	136534KiB (-0.22%)
size-file (stage1)	154596KiB	154424KiB (-0.11%)

https://github.com/llvm/llvm-project/pull/218845