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 {
```

compiler/rustc_expand/src/proc_macro_server.rs

@@ -308,8 +308,8 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
                     }));
                 }
 
-                OpenDelim(..) | CloseDelim(..) => unreachable!(),
-                Eof => unreachable!(),
+                OpenParen | CloseParen | OpenBrace | CloseBrace | OpenBracket | CloseBracket
+                | OpenInvisible(_) | CloseInvisible(_) | Eof => unreachable!(),
             }
         }
         trees