Improve multi-file test framework in CodegenTestCase

Instead of inheriting from KotlinMultiFileTestWithJava, invoke
KotlinTestUtils.createTestFiles directly. This helps to avoid constructing
unnecessary environment (createEnvironment() was called in setUp, but codegen
tests ignored the created environment because it's not possible to do
generically in codegen tests; the environment kind depends on the source file
usually)

compiler/tests/org/jetbrains/kotlin/codegen/AbstractBlackBoxCodegenTest.java

@@ -45,16 +45,15 @@ import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import java.util.Map;
 
 import static org.jetbrains.kotlin.codegen.CodegenTestUtil.compileJava;
 
 public abstract class AbstractBlackBoxCodegenTest extends CodegenTestCase {
     @Override
-    protected void doMultiFileTest(File file, Map<String, ModuleAndDependencies> modules, List<TestFile> files) throws Exception {
+    protected void doMultiFileTest(@NotNull File wholeFile, @NotNull List<TestFile> files, @Nullable File javaFilesDir) throws Exception {
         if (files.size() == 1) {
             createEnvironmentWithMockJdkAndIdeaAnnotations(ConfigurationKind.JDK_ONLY);
-            blackBoxFileByFullPath(file.getPath());
+            blackBoxFileByFullPath(wholeFile.getPath());
         }
         else {
             doTestMultiFile(files);