[FE 1.0] Use the new type intersection emptiness check

Also introduced compatibility mode to preserve compatibility for is/as/equality checks

^KT-29316 Related

compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/ConeInferenceContext.kt

@@ -426,6 +426,8 @@ interface ConeInferenceContext : TypeSystemInferenceExtensionContext, ConeTypeCo
         return withAttributes(attributes.remove(CompilerConeAttributes.Exact))
     }
 
+    override fun KotlinTypeMarker.canHaveSubtypes(typeChecker: AbstractTypeChecker): Boolean? = null
+
     override fun TypeConstructorMarker.toErrorType(): SimpleTypeMarker {
         if (this is ErrorTypeConstructor) return createErrorType(reason)
         if (this is ConeClassLikeLookupTag) return createErrorType("Not found classifier: $classId")