Remove token::{Open,Close}Delim.

By replacing them with `{Open,Close}{Param,Brace,Bracket,Invisible}`.

PR #137902 made `ast::TokenKind` more like `lexer::TokenKind` by
replacing the compound `BinOp{,Eq}(BinOpToken)` variants with fieldless
variants `Plus`, `Minus`, `Star`, etc. This commit does a similar thing
with delimiters. It also makes `ast::TokenKind` more similar to
`parser::TokenType`.

This requires a few new methods:
- `TokenKind::is_{,open_,close_}delim()` replace various kinds of
  pattern matches.
- `Delimiter::as_{open,close}_token_kind` are used to convert
  `Delimiter` values to `TokenKind`.

Despite these additions, it's a net reduction in lines of code. This is
because e.g. `token::OpenParen` is so much shorter than
`token::OpenDelim(Delimiter::Parenthesis)` that many multi-line forms
reduce to single line forms. And many places where the number of lines
doesn't change are still easier to read, just because the names are
shorter, e.g.:
```
-   } else if self.token != token::CloseDelim(Delimiter::Brace) {
+   } else if self.token != token::CloseBrace {
```

src/librustdoc/clean/render_macro_matchers.rs

@@ -96,7 +96,7 @@ fn print_tt(printer: &mut Printer<'_>, tt: &TokenTree) {
             }
         }
         TokenTree::Delimited(_span, _spacing, delim, tts) => {
-            let open_delim = printer.token_kind_to_string(&token::OpenDelim(*delim));
+            let open_delim = printer.token_kind_to_string(&delim.as_open_token_kind());
             printer.word(open_delim);
             if !tts.is_empty() {
                 if *delim == Delimiter::Brace {
@@ -107,7 +107,7 @@ fn print_tt(printer: &mut Printer<'_>, tt: &TokenTree) {
                     printer.space();
                 }
             }
-            let close_delim = printer.token_kind_to_string(&token::CloseDelim(*delim));
+            let close_delim = printer.token_kind_to_string(&delim.as_close_token_kind());
             printer.word(close_delim);
         }
     }