[Test] Add ability to freely transform module structure which was parsed from directive

Service ModuleStructureExtractor may break readabilty of test so it
  should be used very carefully

Originally it is created for box inline test where we have different
  runners on same testdata where one runner assumes that all files
  in test in same module and other that they in different ones

compiler/test-infrastructure/tests/org/jetbrains/kotlin/test/TestInfrastructureInternals.kt

@@ -0,0 +1,14 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.test
+
+/**
+ * This annotation used for marking low-level services of test infrastructure which
+ *   normally should not be used. Please think twice before using something
+ *   marked with this annotation
+ */
+@RequiresOptIn
+annotation class TestInfrastructureInternals

compiler/test-infrastructure/tests/org/jetbrains/kotlin/test/services/ModuleStructureExtractor.kt

@@ -5,11 +5,13 @@
 
 package org.jetbrains.kotlin.test.services
 
+import org.jetbrains.kotlin.test.TestInfrastructureInternals
 import org.jetbrains.kotlin.test.directives.model.DirectivesContainer
 
-abstract class ModuleStructureExtractor(
+abstract class ModuleStructureExtractor @OptIn(TestInfrastructureInternals::class) constructor(
     protected val testServices: TestServices,
-    protected val additionalSourceProviders: List<AdditionalSourceProvider>
+    protected val additionalSourceProviders: List<AdditionalSourceProvider>,
+    protected val moduleStructureTransformers: List<ModuleStructureTransformer>
 ) {
     abstract fun splitTestDataByModules(
         testDataFileName: String,

compiler/test-infrastructure/tests/org/jetbrains/kotlin/test/services/ModuleStructureTransformer.kt

@@ -0,0 +1,13 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.test.services
+
+import org.jetbrains.kotlin.test.TestInfrastructureInternals
+
+@TestInfrastructureInternals
+abstract class ModuleStructureTransformer {
+    abstract fun transformModuleStructure(moduleStructure: TestModuleStructure): TestModuleStructure
+}