Created module idea-test-framework and moved classes needed for idea tests there

Moved tests for completion and their test data into module idea-completion

idea/idea-completion/testData/smart/functionReference/4.kt

@@ -0,0 +1,11 @@
+fun foo(p: (() -> Unit)?){}
+
+fun bar() {
+    foo(<caret>)
+}
+
+fun f1(){}
+fun f2(i: Int){}
+
+// EXIST: ::f1
+// ABSENT: ::f2