[FIR2IR] Create delegated field for delegation to var property

^KT-65920 Fixed

compiler/testData/ir/irText/classes/delegatedGenericImplementation.fir.kt.txt

@@ -26,6 +26,7 @@ class Test1<E : Any?> : IBase<E> {
 }
 
 class Test2 : IBase<String> {
+  private /* final field */ val $$delegate_0: IBase<String> = j
   var j: IBase<String>
     field = j
     get
@@ -38,20 +39,20 @@ class Test2 : IBase<String> {
   }
 
   override fun <B : Any?> foo(a: String, b: B) {
-    <this>.#j.foo<B>(a = a, b = b)
+    <this>.#$$delegate_0.foo<B>(a = a, b = b)
   }
 
   override val <C : Any?> C.id: Map<String, C>?
     override get(): Map<String, C>? {
-      return (<this>.#j, <this>).<get-id><C>()
+      return (<this>.#$$delegate_0, <this>).<get-id><C>()
     }
 
   override var <D : Any?> List<D>.x: D?
     override get(): D? {
-      return (<this>.#j, <this>).<get-x><D>()
+      return (<this>.#$$delegate_0, <this>).<get-x><D>()
     }
     override set(<set-?>: D?) {
-      (<this>.#j, <this>).<set-x><D>(<set-?> = <set-?>)
+      (<this>.#$$delegate_0, <this>).<set-x><D>(<set-?> = <set-?>)
     }
 
 }