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/injava/ClassesFromNamespace.java

@@ -0,0 +1,13 @@
+public class Testing {
+    public static void test() {
+        mockLib.foo.<caret>
+    }
+}
+
+// note: "NUMBER" check also assures that FooPackage$src$ classes are not visible
+
+// EXIST: LibClass
+// EXIST: LibTrait
+// EXIST: LibEnum
+// EXIST: LibObject
+// EXIST: FooPackage