[Tests] FIR support in JUnit 3 tests, port necessary subclasses

^KT-64404 Fixed
^KT-64438 Fixed
^KT-64407 Fixed

compiler/tests/org/jetbrains/kotlin/codegen/ReflectionClassLoaderTest.kt

@@ -18,7 +18,7 @@ package org.jetbrains.kotlin.codegen
 
 import org.jetbrains.kotlin.test.ConfigurationKind
 
-class ReflectionClassLoaderTest : CodegenTestCase() {
+open class ReflectionClassLoaderTest : CodegenTestCase() {
     override fun getPrefix() = "reflection/classLoaders"
 
     override fun setUp() {