Go to definition to function defined by macro with name ending in `?` or `!` does not work

This is a tracking issue for a bug found by a coworker. #759 added support for going to definition to functions defined by a macro. But turns out is only works for functions with "regular" names (for example `MyApp.Repo.one/1`) but not for the ones ending in `?` or `!` (`MyApp.Repo.exists?/1`)

I opened PR to ElixirSense already, but I think current HEAD of it does not pass tests in Expert, so even after the merge we'd have to figure something out (fork and cherry-pick for a time being, perhaps?).

https://github.com/elixir-lsp/elixir_sense/pull/344