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/VariableClassName.kt

@@ -0,0 +1,12 @@
+package some
+
+open class MyClass() {
+}
+
+class A() {
+    public fun test() {
+        val a : MyC<caret>
+    }
+}
+
+// EXIST: MyClass