TypeSystemContext: Rework raw types processing

All the current usages are about checking if the type is raw,
also in K2 it is simply incorrect to assume that only flexible types
might be raw

core/compiler.common/src/org/jetbrains/kotlin/types/TypeSystemCommonBackendContext.kt

@@ -62,8 +62,6 @@ interface TypeSystemCommonBackendContextForTypeMapping : TypeSystemCommonBackend
     fun SimpleTypeMarker.isSuspendFunction(): Boolean
     fun SimpleTypeMarker.isKClass(): Boolean
 
-    fun KotlinTypeMarker.isRawType(): Boolean
-
     fun TypeConstructorMarker.typeWithArguments(arguments: List<KotlinTypeMarker>): SimpleTypeMarker
     fun TypeConstructorMarker.typeWithArguments(vararg arguments: KotlinTypeMarker): SimpleTypeMarker {
         return typeWithArguments(arguments.toList())

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

@@ -356,7 +356,7 @@ interface TypeSystemContext : TypeSystemOptimizationContext {
     fun KotlinTypeMarker.isUninferredParameter(): Boolean
     fun FlexibleTypeMarker.asDynamicType(): DynamicTypeMarker?
 
-    fun FlexibleTypeMarker.asRawType(): RawTypeMarker?
+    fun KotlinTypeMarker.isRawType(): Boolean
     fun FlexibleTypeMarker.upperBound(): SimpleTypeMarker
 
     fun FlexibleTypeMarker.lowerBound(): SimpleTypeMarker