Add warnings at declaration and call sites of operator 'mod'

compiler/testData/diagnostics/tests/regressions/kt629.kt

@@ -4,7 +4,7 @@ package kt629
 
 class A() {
     var p = "yeah"
-    operator fun mod(<!UNUSED_PARAMETER!>other<!> : A) : A {
+    operator fun rem(<!UNUSED_PARAMETER!>other<!> : A) : A {
         return A();
     }
 }

compiler/testData/diagnostics/tests/regressions/kt629.txt

@@ -9,7 +9,7 @@ package kt629 {
         public final var p: kotlin.String
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-        public final operator fun mod(/*0*/ other: kt629.A): kt629.A
+        public final operator fun rem(/*0*/ other: kt629.A): kt629.A
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 }