[clang-tools-extra] [clangd] Add 'apply all clangd fixes' and 'apply all '_' fixes' QuickFixes (PR #79867)

[Tor Shepherd via cfe-commits]

torshepherd wrote:

Also, I noticed that the conversion function `toCodeAction(const Fix& F, ...)` specifically hardcodes all Fix objects to `QUICKFIX_KIND`. When we do https://github.com/clangd/clangd/issues/1446, it would be good to add a string for `SOURCE_FIX_ALL_KIND` and set these fix-alls to that `kind`

https://github.com/llvm/llvm-project/pull/79867