[Parcelize] Remove dependency from backend module to k2 module

This is needed to avoid dependencies on FIR classes inside Parcelize IDE
  plugin

plugins/parcelize/parcelize-compiler/parcelize.k2/src/org/jetbrains/kotlin/parcelize/fir/FirParcelizeDeclarationGenerator.kt

@@ -179,7 +179,7 @@ class FirParcelizeDeclarationGenerator(session: FirSession) : FirDeclarationGene
     }
 
     private val key: GeneratedDeclarationKey
-        get() = FirParcelizePluginKey
+        get() = ParcelizePluginKey
 
     override fun FirDeclarationPredicateRegistrar.registerPredicates() {
         register(PREDICATE)

plugins/parcelize/parcelize-compiler/parcelize.k2/src/org/jetbrains/kotlin/parcelize/fir/FirParcelizePluginKey.kt

@@ -1,14 +0,0 @@
-/*
- * 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.parcelize.fir
-
-import org.jetbrains.kotlin.GeneratedDeclarationKey
-
-object FirParcelizePluginKey : GeneratedDeclarationKey() {
-    override fun toString(): String {
-        return "FirParcelize"
-    }
-}