Initial support for KT-7090 Completion for callable references

#KT-7090 Fixed

idea/idea-completion/testData/handlers/basic/callableReference/EmptyQualifier.kt

@@ -0,0 +1,9 @@
+fun globalFun(p: Int) {}
+
+class C {
+    fun foo() {
+        val v = ::<caret>
+    }
+}
+
+// ELEMENT: globalFun