Allow to create quickfix multifile tests in single file

It simplifies creating new tests

idea/testData/quickfix/autoImports/importInFirstPartInUserType.after.kt

@@ -1,7 +0,0 @@
-// "Import" "true"
-// ERROR: Unresolved reference: Some
-package testing
-
-import some.Some
-
-class TestClass: <caret>Some.InnerInSome()

idea/testData/quickfix/autoImports/importInFirstPartInUserType.before.Dependency.kt

@@ -1,7 +0,0 @@
-package some
-
-public class Some {
-  public open class InnerInSome {
-
-  }
-}

idea/testData/quickfix/autoImports/importInFirstPartInUserType.before.Main.kt

@@ -1,5 +0,0 @@
-// "Import" "true"
-// ERROR: Unresolved reference: Some
-package testing
-
-class TestClass: <caret>Some.InnerInSome()

idea/testData/quickfix/autoImports/importInFirstPartInUserType.test

@@ -0,0 +1,28 @@
+// FILE: first.before.kt
+// "Import" "true"
+// ERROR: Unresolved reference: Some
+package testing
+
+class TestClass: <caret>Some.InnerInSome()
+
+
+
+// FILE: second.kt
+package some
+
+public class Some {
+  public open class InnerInSome {
+
+  }
+}
+
+
+
+// FILE: first.after.kt
+// "Import" "true"
+// ERROR: Unresolved reference: Some
+package testing
+
+import some.Some
+
+class TestClass: <caret>Some.InnerInSome()