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/smartMultiFile/GenericInheritors2/GenericInheritors2.kt

@@ -0,0 +1,8 @@
+import p.*
+
+fun foo(): KotlinTrait<I1, I1> {
+    return <caret>
+}
+
+// EXIST: { lookupString: "object", itemText: "object: KotlinTrait<I1, I1>{...}" }
+// EXIST: { lookupString: "KotlinInheritor", itemText: "KotlinInheritor<I1>", tailText: "() (p)" }