K2: repeat K1 representation for flexible type parameters

This commit changes the behavior of KT-59138 effectively declining it in 2.0.
However, we plan to implement KT-59138 behavior under a feature
flag in 2.0 (see KT-66447), and switch this feature on version 2.x.

Also, this commit implements the LC resolution about postponing
KT-57014 change. We don't have KT-57014 described behavior in 2.0 anymore.
However, we plan to implement a deprecation warning here, see KT-65578.

After this commit, 6 diagnostic tests become incorrectly broken:
- 5 tests from PurelyImplementedCollection group
- a test platformTypes/nullableTypeArgument.kt

This commit also breaks currently fixed-in-k2 KT-50134
(it is fixed again in the following commits),
as well as KT-58933 (it will remain not fixed till we enable KT-59138
behavior again).

#KT-65596 In Progress
#KT-57014 In Progress
#KT-58933 Submitted

compiler/fir/analysis-tests/testData/resolve/smartcasts/problems/smartcastToStarProjectedSubclass.kt

@@ -15,7 +15,7 @@ public interface Option<T> {
 // FILE: test.kt
 fun test_1(option: Option<Pair<String, String>>?) {
     if (option is Option.Some<*>) {
-        val x = <!DEBUG_INFO_EXPRESSION_TYPE("CapturedType(*)!! & kotlin.Pair<kotlin.String, kotlin.String>..CapturedType(*)? & kotlin.Pair<kotlin.String, kotlin.String>?")!>option.get()<!>.first
+        val x = <!DEBUG_INFO_EXPRESSION_TYPE("CapturedType(*) & kotlin.Pair<kotlin.String, kotlin.String>..CapturedType(*)? & kotlin.Pair<kotlin.String, kotlin.String>?")!>option.get()<!>.first
         x.length
     }
 }