Rollup merge of #135882 - hkBst:master, r=estebank

simplify `similar_tokens` from `Option<Vec<_>>` to `&[_]`

All uses immediately invoke contains, so maybe a further simplification is possible.

compiler/rustc_parse/src/parser/expr.rs

@@ -3114,9 +3114,8 @@ impl<'a> Parser<'a> {
             let span_before_body = this.prev_token.span;
             let arm_body;
             let is_fat_arrow = this.check(exp!(FatArrow));
-            let is_almost_fat_arrow = TokenKind::FatArrow
-                .similar_tokens()
-                .is_some_and(|similar_tokens| similar_tokens.contains(&this.token.kind));
+            let is_almost_fat_arrow =
+                TokenKind::FatArrow.similar_tokens().contains(&this.token.kind);
 
             // this avoids the compiler saying that a `,` or `}` was expected even though
             // the pattern isn't a never pattern (and thus an arm body is required)