FIR type enhancement: make J2K mapping and changed handling more exact

Related to KT-29937

compiler/testData/loadJava/compiledJava/library/LoadIterable.fir.txt

@@ -1,6 +1,6 @@
 <T> public abstract interface LoadIterable : R|java/lang/Object| {
-    public abstract operator function getIterable(): R|ft<kotlin/collections/MutableIterable<ft<T, T?>>, kotlin/collections/Iterable<ft<T, T?>>>|
+    public abstract operator function getIterable(): R|ft<kotlin/collections/MutableIterable<ft<T, T?>>, kotlin/collections/Iterable<ft<T, T?>>?>|!
 
-    public abstract operator function setIterable(Iterable: R|ft<kotlin/collections/MutableIterable<ft<T, T?>>, kotlin/collections/Iterable<ft<T, T?>>>|): R|kotlin/Unit|
+    public abstract operator function setIterable(Iterable: R|ft<kotlin/collections/MutableIterable<ft<T, T?>>, kotlin/collections/Iterable<ft<T, T?>>?>|!): R|kotlin/Unit|
 
 }

compiler/testData/loadJava/compiledJava/library/LoadIterator.fir.txt

@@ -1,6 +1,6 @@
 <T> public abstract interface LoadIterator : R|java/lang/Object| {
-    public abstract operator function getIterator(): R|ft<kotlin/collections/MutableIterator<ft<T, T?>>, kotlin/collections/Iterator<ft<T, T?>>>|
+    public abstract operator function getIterator(): R|ft<kotlin/collections/MutableIterator<ft<T, T?>>, kotlin/collections/Iterator<ft<T, T?>>?>|!
 
-    public abstract operator function setIterator(iterator: R|ft<kotlin/collections/MutableIterator<ft<T, T?>>, kotlin/collections/Iterator<ft<T, T?>>>|): R|kotlin/Unit|
+    public abstract operator function setIterator(iterator: R|ft<kotlin/collections/MutableIterator<ft<T, T?>>, kotlin/collections/Iterator<ft<T, T?>>?>|!): R|kotlin/Unit|
 
 }

compiler/testData/loadJava/compiledJava/library/Max.fir.txt

@@ -1,4 +1,4 @@
 public open class Max : R|java/lang/Object| {
-    public open operator function max(coll: R|ft<java/util/Collection<out T>, java/util/Collection<out T>?>|!): R|ft<T, T?>|!
+    public open operator function max(coll: R|ft<kotlin/collections/MutableCollection<out T>, kotlin/collections/Collection<out T>?>|!): R|ft<T, T?>|!
 
 }