Replace ast::TokenKind::BinOp{,Eq} and remove BinOpToken.

`BinOpToken` is badly named, because it only covers the assignable
binary ops and excludes comparisons and `&&`/`||`. Its use in
`ast::TokenKind` does allow a small amount of code sharing, but it's a
clumsy factoring.

This commit removes `ast::TokenKind::BinOp{,Eq}`, replacing each one
with 10 individual variants. This makes `ast::TokenKind` more similar to
`rustc_lexer::TokenKind`, which has individual variants for all
operators.

Although the number of lines of code increases, the number of chars
decreases due to the frequent use of shorter names like `token::Plus`
instead of `token::BinOp(BinOpToken::Plus)`.

compiler/rustc_parse/src/parser/mod.rs

@@ -813,9 +813,9 @@ impl<'a> Parser<'a> {
         self.is_keyword_ahead(0, &[kw::Const])
             && self.look_ahead(1, |t| match &t.kind {
                 // async closures do not work with const closures, so we do not parse that here.
-                token::Ident(kw::Move | kw::Static, IdentIsRaw::No)
-                | token::OrOr
-                | token::BinOp(token::Or) => true,
+                token::Ident(kw::Move | kw::Static, IdentIsRaw::No) | token::OrOr | token::Or => {
+                    true
+                }
                 _ => false,
             })
     }
@@ -1651,7 +1651,7 @@ impl<'a> Parser<'a> {
     /// `::{` or `::*`
     fn is_import_coupler(&mut self) -> bool {
         self.check_path_sep_and_look_ahead(|t| {
-            matches!(t.kind, token::OpenDelim(Delimiter::Brace) | token::BinOp(token::Star))
+            matches!(t.kind, token::OpenDelim(Delimiter::Brace) | token::Star)
         })
     }