Refactor & improve handling of overloaded binary operators

Fixes #9971. Also records them as method resolutions, which we could use
later.

crates/hir_expand/src/name.rs

@@ -285,6 +285,33 @@ pub mod known {
         wrapping_add,
         wrapping_mul,
         wrapping_sub,
+        // known methods of lang items
+        add,
+        mul,
+        sub,
+        div,
+        rem,
+        shl,
+        shr,
+        bitxor,
+        bitor,
+        bitand,
+        add_assign,
+        mul_assign,
+        sub_assign,
+        div_assign,
+        rem_assign,
+        shl_assign,
+        shr_assign,
+        bitxor_assign,
+        bitor_assign,
+        bitand_assign,
+        eq,
+        ne,
+        ge,
+        gt,
+        le,
+        lt,
     );
 
     // self/Self cannot be used as an identifier