Rollup merge of #67010 - estebank:raw-idents, r=Centril

Accurately portray raw identifiers in error messages

When refering to or suggesting raw identifiers, refer to them with `r#`.

Fix #65634.

src/librustc/ty/print/pretty.rs

@@ -1282,6 +1282,9 @@ impl<F: fmt::Write> Printer<'tcx> for FmtPrinter<'_, 'tcx, F> {
             if !self.empty_path {
                 write!(self, "::")?;
             }
+            if ast::Ident::from_str(&name).is_raw_guess() {
+                write!(self, "r#")?;
+            }
             write!(self, "{}", name)?;
 
             // FIXME(eddyb) this will print e.g. `{{closure}}#3`, but it