RemoveUnusedBinding offers to remove unused parameters but doesn't remove them

[baronfel]

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

I think this reported issue/feature gap in FSAC is reproducible in the VS tooling as well.

For the code:

let inc i =
    2

with --warnon:1182 enabled, there will be a diagnostic issued for the parameter i, but the current codefix will not handle this scenario.

Describe the solution you'd like

I think a small change to the TryRangeOfBindingWithHeadPatternWithPos member could be made very similarly to what I've done in this PR, and the range that is derived from this member could be tagged as coming from a pattern or a binding.

Then, later in the codefix that result would be inspected to walk the text in slightly different ways for patterns and bindings, so that both kinds of triggering entities for this diagnostic could be handled.

Describe alternatives you've considered

Not doing this work, so that only nested bindings are removable.

[psfinaki]

Hah this has somehow transformed into a bug as of now - as the fix is suggested but not applied.

bug.mp4

[psfinaki]

There are a few extra things to consider here:

1. Spacing
2. Parameters can have explicit types specifies - they should be removed as well
3. Removing a parameter in one-parameter function shouldn't turn the function into a value (let f x = 42 -> let f() = 42)