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/weighers/basic/AfterNullable.kt

@@ -0,0 +1,11 @@
+fun String?.forNullableString(){}
+fun Any?.forNullableAny(){}
+fun String.forString(){}
+
+fun foo(s: String?) {
+    s.for<caret>
+}
+
+// ORDER: forNullableString
+// ORDER: forNullableAny
+// ORDER: forString