Resolve callable reference expressions

#KT-1183 In Progress

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

@@ -0,0 +1,8 @@
+fun foo(x: Int, <!UNUSED_PARAMETER!>y<!>: Any) = x
+fun foo(<!UNUSED_PARAMETER!>x<!>: Any, y: Int) = y
+
+fun main() {
+    ::<!OVERLOAD_RESOLUTION_AMBIGUITY!>foo<!>
+    
+    ::<!OVERLOAD_RESOLUTION_AMBIGUITY!>foo<!> : (Int, Any) -> Unit
+}