feat: Add "Bind unused parameter" assist

[vsrs]

This PR introduces a new Bind unused parameter assistant.

While we do have a QuickFix from rustc (prefixing the parameter with an underscore), it's sometimes more convenient to suppress the warning using the following approach:

 fn some_function(unused: i32) {}

->

fn some_function(unused: i32) {
    let _ = unused;
}

[Veykril]

Would be nice to have this as a diagnostic quickfix oncew e have a diagnostic for unused vars

[vsrs]

Would be nice to have this as a diagnostic quickfix oncew e have a diagnostic for unused vars

remove_unused_param assist from

rust-analyzer/crates/ide-assists/src/handlers/remove_unused_param.rs

Line 78 in 62268e4

AssistId("remove_unused_param", AssistKind::Refactor),

has AssistKind::Refactor kind; I belive it's worth to have the same (or change both to QuickFix)

[Veykril]

Yes, that one I'd say should also ideally be a diagnostic quickfix, but that's a different issue not relevant to this right now

[vsrs]

Just realized that this assist is different from 'remove_unused_param' one and can work for trait impl methods too. So, rollbacked all refactorings in remove_unused_param code.

[Veykril]

@bors r+

[bors]

📌 Commit 1eb6d2e has been approved by Veykril

It is now in the queue for this repository.

[bors]

⌛ Testing commit 1eb6d2e with merge 829e777...

[bors]

☀️ Test successful - checks-actions
Approved by: Veykril
Pushing 829e777 to master...