Discover/link positional [de]construction

Given a code like this it would be great to get cross-references:
```haskell
data Foo = Foo { x :: Int, y :: Double }

foo = Foo 1 2

bar (Foo x _) = x
```

E.g., when one clicks on `x` in data definition both `foo` and `bar` are useful places to link to because they "use" `x`. For bonus points it would be great to not link `_` in `bar` when `y` is clicked.

As a workaround, clicking on the data constructor name currently works, so this issue is a pure usability enhancement, not a particularly critical enabler.