Associate `.new` and `#initialize` methods

[soutaro]

Let's investigate how we can connect new and initialize. Hopefully, we can do it in a generic way that allows connecting other methods where we have a pattern that the method call doesn't match the user definition.

Another example is Active Job's perform (definition) and perform_now or perform_later (call).

[soutaro]

Random note on this:

• Should we insert declarations for .new methods?
• Should we insert declarations for empty singleton classes?

It feels like generating necessary data upon query would be better, but the data representation (especially for the Ruby client) seems complicated because it should miss the declaration id.

[soutaro]

This is already handled in ruby-lsp.