Implement asList, slice & sliceArray extension functions for UArrays

generators/builtins/unsignedTypes.kt

@@ -454,8 +454,7 @@ class UnsignedArrayGenerator(val type: UnsignedType, out: PrintWriter) : BuiltIn
     }
 
     override fun containsAll(elements: Collection<$elementType>): Boolean {
-        if ((elements as Collection<Any?>).any { it as? $elementType == null }) return false
-        return elements.all { storage.contains(it.to$storageElementType()) }
+        return (elements as Collection<*>).all { it is $elementType && storage.contains(it.to$storageElementType()) }
     }
 
     override fun isEmpty(): Boolean = this.storage.size == 0"""