New J2K: implement mutability inference in post-processing

#KT-24293 fixed
#KT-19603 fixed

nj2k/testData/inference/common/forLoop.kt

@@ -7,4 +7,4 @@ fun test() {
 
 //T0 <: T1 due to 'INITIALIZER'
 //T2 <: T4 due to 'INITIALIZER'
-//T3 <: T1 due to 'ASSIGNMENT'
+//T1 <: T3 due to 'ASSIGNMENT'

nj2k/testData/inference/common/newExpression.kt

@@ -0,0 +1,5 @@
+class Test {
+    val x: /*T2@*/List</*T1@*/Int> = ArrayList</*T0@*/Int>()/*ArrayList<T0@Int>*/
+}
+
+//T1 := T0 due to 'INITIALIZER'