[clang-tools-extra] Add support for renaming objc methods, even those with multiple selector pieces (PR #76466)

[Ben Barham via cfe-commits]

https://github.com/bnbarham commented:

Cool stuff @DavidGoldman! Nice to see ObjC getting some love. It's a bummer we duplicated here, but seems like both you and @ahoppen took fairly similar approaches. The main difference looks to be the use of `SymbolName` in the other PR.

https://github.com/llvm/llvm-project/pull/76466