Investigate the possibility of add-ons enhancing find references

[vinistock]

There are certain situations where references to declarations may exist in a DSL form. For example, in Rails, if you were to rename/find references for a model, then associations made to that model should be included as well.

class Post
end

class User
  has_many :posts # <<< this should be counted as a reference to the `Post` class, despite being a symbol
end

We will need to study what use cases exist and how to allow for this. Maybe this should be a concern of indexing enhancements and we should expedite the work to merge the reference finder with the declaration listener.