Rollup merge of #133201 - nnethercote:rm-TokenKind-InvalidPrefix, r=compiler-errors

Remove `TokenKind::InvalidPrefix`

It's not needed. Best reviewed one commit at a time.

r? `@estebank`

Author: matthiaskrgr

crates/parser/src/lexed_str.rs

@@ -183,7 +183,7 @@ impl<'a> Converter<'a> {
                 rustc_lexer::TokenKind::Ident => {
                     SyntaxKind::from_keyword(token_text, self.edition).unwrap_or(IDENT)
                 }
-                rustc_lexer::TokenKind::InvalidPrefix | rustc_lexer::TokenKind::InvalidIdent => {
+                rustc_lexer::TokenKind::InvalidIdent => {
                     err = "Ident contains invalid characters";
                     IDENT
                 }