ChannelMessageDeleteWsRequest constructor Null safety

1. sendbird_sdk
2. message_delete_request
3. ChannelMessageDeleteWsRequest
4. ChannelMessageDeleteWsRequest constructor

ChannelMessageDeleteWsRequest class

1. Constructors
2. ChannelMessageDeleteWsRequest
3. Properties
4. cmd
5. encoded
6. hashCode
7. isAckRequired
8. payload
9. requestId
10. runtimeType
11. Methods
12. noSuchMethod
13. toString
14. Operators
15. operator ==