Add local definitions to outline

[sgillespie]

Addresses #3628. Adds all local symbols (functions/vars) as children to function document symbols.

There are a few potential issues:

1. The position/range points to the toplevel function
2. getFuzzyScope might be abused here (should I create another function like getLocalScope?)

Thoughts?

[sgillespie]

This is what the outline looks like in emacs (via imenu-list)

For a bit of extra context, here is one of the definitions:

f :: a -> a
f x = g x
  where
    g = id
    h = id

[michaelpj]

A test case I'd like to see

f 1 = g
  where g = 2
f _ = g 
  where g = 3