serializer function requires useless parameters for abstract and sealed classes

[shanshin]

Describe the bug serializer function expects generic type serializer but not use it inside

To Reproduce

    @Serializable
    abstract class TypedAbstractClass<T>

and when trying to get the serializer its need to specify one argument TypedAbstractClass.serializer(SomeClass.serializer)

Same for sealed class.

Expected behavior serializer function without parameters

Environment

• Kotlin version: 1.4.30-M1
• Library version: 1.0.1
• Kotlin platforms: all

[sandwwraith]

Related: #1531