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/NestedLocalClassCompletion.kt.after

@@ -0,0 +1,7 @@
+fun foo() {
+    class LocalClass {
+        inner class Nested {}
+
+        val v: Nested<caret>
+    }
+}