Inlay hints for unmatched patterns on wild cards.

[MangoIV]

Is your enhancement request related to a problem? Please describe.

say I have a function

data X = A | B | C | D 

f :: X -> X -> Bool 
f A A = True 
f _ _ = False

Then sometimes it is not obvious, what kind patterns are subsumed by the wildcards.

Describe the solution you'd like

What would be really cool would be to have HLS show the patterns that haven't been matched as inlay hint on the wildcards.

This would be similar to what the warning shows when just omitting the cases.

Describe alternatives you've considered

Additional context