Add lifetime-aware support for Display impl of Ident

[xizheyin]

Fixes #143150

r? compiler

[xizheyin]

@rustbot ready

[xizheyin]

When Ident starts with ', the contents are printed recursively.

[xizheyin]

There are two keywords that need to be excluded here.

[xizheyin]

The label needs to be converted to String, otherwise the error message will call to_ident_string, which will print 'break as 'r#break in the following example.

fn main() {
    'break: loop { //~ ERROR invalid label name `'break`
    }
}

I haven't checked to see if there are any other label-related errors yet though, there may be similar issues, but it's generally a more borderline case.

[fmease]

(Oh interesting. 'break is actually an invalid label but 'r#break is only a valid label in Rust >=2021) (ignore, not relevant)

[fmease]

Ah, you should be able to use Symbol instead of String here (doesn't make much of a difference here tho) (we could actually suggest escaping via r# (if we have Rust >= 2021) here but that's for another PR)

[xizheyin]

I found the implementation of Symbol as diagnostic arguments.

rust/compiler/rustc_errors/src/diagnostic_impls.rs

Lines 165 to 169 in f191420

	impl IntoDiagArg for Symbol {
	fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
	self.to_ident_string().into_diag_arg(path)
	}
	}

It will be transformed to Ident, so if I use Symbol here, It prints invalid label name 'r#break. I may have to use String.