[clangd] Fix renaming single argument ObjC methods (#82396)

Use the legacy non-ObjC rename logic when dealing with selectors that
have zero or one arguments. In addition, make sure we don't add an extra
`:` during the rename.

Add a few more tests to verify this works (thanks to @ahoppen for the
tests and finding this bug).

GitOrigin-RevId: 59e5519c81c57a66424d657864ce69cb0efdc7d8
2 files changed