cannot rename implicit parameters

If my cursor is over `?x` in the file below, a prompt can come up to rename `x`, but it doesn't change the file. I use hls 1.8
```
{-# LANGUAGE ImplicitParams #-}
a = let ?x = 3 in ?x
```
If you select a single `?x` to rename to `?y`, I see two options:
```
aa = (let ?x = 3 in ?x, let ?x = 2 in ?x) -- original
aa = (let ?y = 3 in ?y, let ?x = 2 in ?x) -- scoped rename
aa = (let ?y = 3 in ?y, let ?y = 2 in ?y) -- global rename
```
I would prefer "Scoped" for consistency with regular variables.