Check if clippy::used_underscore_binding is allowed on the underscore field

[xFrednet]

Description

It would be cool, if the clippy::used_underscore_binding lint would also check the lint level at the field itself. This would make it simple to allow the lint, if it's used by a derive macro

Example

#![warn(clippy::used_underscore_binding)]

pub struct Bar {
    // This allow should also suppress the lint
    // vvv
    #[allow(clippy::used_underscore_binding)]
    _cool: u32,
}

impl Bar {
    pub fn something(&self) {
        println!("{}", self._cool);
    } 
}

Hints:

The lint level at a given note, can be checked with TyCtxt::lint_level_at_node accessed via cx.tcx.lint_level_at_node with the HirId of the field. If the level is Level::Expect, the expectation should be marked as fulfilled by calling LateContext::fulfill_expectation

Version

1.74.0

Additional Information

Context: idanarye/rust-typed-builder#113

[Alexendoo]

Ignoring phantom data fields is probably also reasonable. I'll take a stab at this one, might be a little tricky to get to the field definition from the usage site

[xFrednet]

You should be able to get the type of self and then fetch the struct definition with field information from that. And you just created a PR xD