K2: Imitate K1 behavior for case of captured types with a raw supertype

See the comments in the code, but mostly the motivation is that once
it was decided to stick with such a legacy thing as raw types,
we are ok with some corner-cases hacks for them
(if there are not too many of them) and they don't break anything
when there are no raw types in the code.

^KT-56616 Fixed

core/compiler.common/src/org/jetbrains/kotlin/types/model/TypeSystemContext.kt

@@ -312,6 +312,11 @@ interface TypeSystemInferenceExtensionContext : TypeSystemContext, TypeSystemBui
      */
     fun useRefinedBoundsForTypeVariableInFlexiblePosition(): Boolean
 
+    /**
+     * It's only relevant for K2 (and is not expected to be implemented properly in other contexts)
+     */
+    fun KotlinTypeMarker.convertToNonRaw(): KotlinTypeMarker
+
     fun createCapturedStarProjectionForSelfType(
         typeVariable: TypeVariableTypeConstructorMarker,
         typesForRecursiveTypeParameters: List<KotlinTypeMarker>,
@@ -357,6 +362,7 @@ interface TypeSystemContext : TypeSystemOptimizationContext {
     fun FlexibleTypeMarker.asDynamicType(): DynamicTypeMarker?
 
     fun KotlinTypeMarker.isRawType(): Boolean
+
     fun FlexibleTypeMarker.upperBound(): SimpleTypeMarker
 
     fun FlexibleTypeMarker.lowerBound(): SimpleTypeMarker

core/descriptors/src/org/jetbrains/kotlin/types/checker/ClassicTypeSystemContext.kt

@@ -158,6 +158,10 @@ interface ClassicTypeSystemContext : TypeSystemInferenceExtensionContext, TypeSy
         return this is RawType
     }
 
+    override fun KotlinTypeMarker.convertToNonRaw(): KotlinTypeMarker {
+        error("Is not expected to be called in K1")
+    }
+
     override fun FlexibleTypeMarker.upperBound(): SimpleTypeMarker {
         require(this is FlexibleType, this::errorMessage)
         return this.upperBound