Prohibit callable references to object members

To be able to make them more useful in the future, i.e. bound to the object
instance

compiler/testData/diagnostics/tests/callableReference/objectMembersUnsupported.kt

@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+import Obj.ext
+import A.Companion.ext2
+
+object Obj {
+    fun foo() {}
+    val bar = 2
+    val String.ext: String get() = this
+}
+
+class A {
+    companion object {
+        fun foo() {}
+        val bar = 2
+        val String.ext2: String get() = this
+    }
+}
+
+fun test() {
+    Obj::<!CALLABLE_REFERENCE_TO_OBJECT_MEMBER!>foo<!>
+    Obj::<!CALLABLE_REFERENCE_TO_OBJECT_MEMBER!>bar<!>
+    String::<!CALLABLE_REFERENCE_TO_OBJECT_MEMBER!>ext<!>
+
+    A.Companion::<!CALLABLE_REFERENCE_TO_OBJECT_MEMBER!>foo<!>
+    A.Companion::<!CALLABLE_REFERENCE_TO_OBJECT_MEMBER!>bar<!>
+    String::<!CALLABLE_REFERENCE_TO_OBJECT_MEMBER!>ext2<!>
+
+    A::<!UNRESOLVED_REFERENCE!>foo<!>
+    A::<!UNRESOLVED_REFERENCE!>bar<!>
+}

compiler/testData/diagnostics/tests/callableReference/objectMembersUnsupported.txt

@@ -0,0 +1,30 @@
+package
+
+public fun test(): kotlin.Unit
+
+public final class A {
+    public constructor A()
+    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 open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    public companion object Companion {
+        private constructor Companion()
+        public final val bar: kotlin.Int = 2
+        public final val kotlin.String.ext2: kotlin.String
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public final fun foo(): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+}
+
+public object Obj {
+    private constructor Obj()
+    public final val bar: kotlin.Int = 2
+    public final val kotlin.String.ext: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final fun foo(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}