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/basic/common/ImmediateMembers4.kt

@@ -0,0 +1,16 @@
+trait T {
+    fun foo1(){}
+    fun foo2(){}
+}
+
+class B(worker: T) : T by worker {
+    override fun foo1() { }
+}
+
+fun foo(b: B) {
+    b.<caret>
+}
+
+// EXIST: { itemText: "foo1", attributes: "bold" }
+// EXIST: { itemText: "foo2", attributes: "" }
+// EXIST: { itemText: "equals", attributes: "" }