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/stmt.rs

@@ -442,7 +442,16 @@ impl<'a> Parser<'a> {
     /// Parses the RHS of a local variable declaration (e.g., `= 14;`).
     fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option<P<Expr>>> {
         let eq_consumed = match self.token.kind {
-            token::BinOpEq(..) => {
+            token::PlusEq
+            | token::MinusEq
+            | token::StarEq
+            | token::SlashEq
+            | token::PercentEq
+            | token::CaretEq
+            | token::AndEq
+            | token::OrEq
+            | token::ShlEq
+            | token::ShrEq => {
                 // Recover `let x <op>= 1` as `let x = 1` We must not use `+ BytePos(1)` here
                 // because `<op>` can be a multi-byte lookalike that was recovered, e.g. `➖=` (the
                 // `➖` is a U+2796 Heavy Minus Sign Unicode Character) that was recovered as a
@@ -688,7 +697,7 @@ impl<'a> Parser<'a> {
             if self.token == token::Eof {
                 break;
             }
-            if self.is_vcs_conflict_marker(&TokenKind::BinOp(token::Shl), &TokenKind::Lt) {
+            if self.is_vcs_conflict_marker(&TokenKind::Shl, &TokenKind::Lt) {
                 // Account for `<<<<<<<` diff markers. We can't proactively error here because
                 // that can be a valid path start, so we snapshot and reparse only we've
                 // encountered another parse error.