Add support for going to definition of overloaded labels as field lenses

`optics-core` supports using overloaded labels as field lenses (and constructor prisms) for types with a `Generic` instance since 0.4.

Consider the following module (full project for ease of reproducibility is [here](https://github.com/arybczak/hls-optics-test)).

```haskell
{-# LANGUAGE DeriveGeneric, OverloadedLabels #-}
module Main where

import Optics.Core
import GHC.Generics (Generic)

data User p = User { name :: String, age :: Int }
deriving (Show, Generic)

getName_gotoWorks :: User p -> String
getName_gotoWorks u = name u

getName_gotoDoesntWork :: User p -> String
getName_gotoDoesntWork u = u ^. #name

setFields_ambiguousMiddleType :: User p -> User p
setFields_ambiguousMiddleType u = u & #name .~ "Tom"
& #age .~ 45

main :: IO ()
main = pure ()
```

With `name` in the definition of `getName_gotoWorks` jumping to the definition works fine. However, trying to do the same using `#name` within `getName_gotoDoesntWork` doesn't.

Would it be possible to add a support for this? On hover the term `#name` is a dictionary for `IsLabel "name" (Optic' A_Lens NoIx (User p) String)`, so in principle it's possible to go to the field definition as all the information is there.

A somewhat more complicated case is in `setFields_ambiguousMiddleType`: hovering over `#name` there shows just `IsLabel`, presumably due to undetermined phantom type variable (since getting rid of the type variable show the full type) :thinking: Hovering over `#age` gives all the dictionary info (`IsLabel "age" (Optic A_Lens NoIx (User Any) (User p) Int Int`).

Output of `haskell-language-server --probe-tools`:
```
haskell-language-server version: 1.0.0.0 (GHC: 8.10.4) (PATH: /home/unknown/.cabal/store/ghc-8.10.4/haskell-language-server-1.0.0.0-e-haskell-language-server-789994ec071fd92b667a696b70ccf6882ad277e8ef1bfac3a85c7a034386e70e/bin/haskell-language-server)
Tool versions found on the $PATH
cabal: 3.4.0.0
stack: 2.3.3
ghc: 8.10.4
```