QuickFixMultiModule: change tests structure

idea/testData/multiModuleQuickFix/other/memberValToExtensionByHeader/header/header.kt

@@ -0,0 +1,5 @@
+// "Convert member to extension" "true"
+
+expect class Foo {
+    val <caret>foo: Int
+}

idea/testData/multiModuleQuickFix/other/memberValToExtensionByHeader/header/header.kt.after

@@ -0,0 +1,6 @@
+// "Convert member to extension" "true"
+
+expect class Foo {
+}
+
+expect val Foo.foo: Int