Fix remaining issues in raw identifiers

[ironcev]

The should_pass/language/raw_identifiers test extended in #7137 pointed out several issues in the handling of raw identifiers. To reproduce them, uncomment the code marked as TODO linking to this issue. Below is the summary.

If there is a raw ident variable with the same name as a row ident function, the function call fails with the error that the declaration is not a function but a variable:

let v = r#fn(r#fn);

Struct instantiation of a raw-ident named struct cannot find the struct:

let v = r#struct {
    r#u64: 42,
};

Enum instantiation of a raw-ident named enum cannot find the enum:

r#enum::r#bool(false)

[pheobeayo]

I’d like to work on this.

[BlessingEmejulu]

Could I take over this issue?

[7gbice]

I’d like to resolve this.