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/handlers/InnerClass.kt

@@ -0,0 +1,7 @@
+class C {
+    inner class Inner(s: String)
+}
+
+fun foo(c: C) {
+    c.<caret>
+}