Fix remaining issues in raw identifiers

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:
```sway
let v = r#fn(r#fn);
```

Struct instantiation of a raw-ident named struct cannot find the struct:
```sway
let v = r#struct {
r#u64: 42,
};
```

Enum instantiation of a raw-ident named enum cannot find the enum:
```sway
r#enum::r#bool(false)
```

Start with the should_pass/language/raw_identifiers test and uncomment the TODO cases linked to this issue. Run the test to reproduce the function-call, struct-instantiation, and enum-instantiation failures, then trace the compiler's raw-identifier handling. Done means all listed examples compile or resolve correctly.

Written by the indexing model from the issue text.