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/InClassObject.kt

@@ -0,0 +1,25 @@
+class C {
+    val field = 0
+    class NestedClass
+    inner class InnerClass
+    object AnObject
+
+    companion object {
+        val classObjectField = 0
+        class ClassObjectClass
+
+        fun foo(){
+            <caret>
+        }
+    }
+}
+
+fun C.extensionForC(){}
+
+// ABSENT: field
+// EXIST: NestedClass
+// EXIST: InnerClass
+// EXIST: AnObject
+// EXIST: classObjectField
+// EXIST: ClassObjectClass
+// ABSENT: extensionForC