Revert "[light classes] drop old light classes and backend: iteration #7"

This reverts commit 545a316241.

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/builder/LightClassBuilder.kt

@@ -60,6 +60,8 @@ fun buildLightClass(
         generate(state, files)
 
         val javaFileStub = classBuilderFactory.result()
+
+        stubComputationTrackerInstance(project)?.onStubComputed(javaFileStub, context)
         return LightClassBuilderResult(javaFileStub, context.bindingContext, state.collectedExtraJvmDiagnostics)
     } catch (e: ProcessCanceledException) {
         throw e

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/builder/stubComputationTracker.kt

@@ -0,0 +1,17 @@
+/*
+ * Copyright 2010-2022 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.cli.jvm.compiler.builder
+
+import com.intellij.openapi.project.Project
+import com.intellij.psi.impl.java.stubs.PsiJavaFileStub
+
+fun stubComputationTrackerInstance(project: Project): StubComputationTracker? {
+    return project.getComponent(StubComputationTracker::class.java)
+}
+
+interface StubComputationTracker {
+    fun onStubComputed(javaFileStub: PsiJavaFileStub, context: LightClassConstructionContext)
+}