Nip57 - Lightning Zaps

[avlo]

continuing NIP57 implementation: - new classes per this branch - updating/evolving existing implementation - new Kind added for zaps - minor refactor in NIP01

culled unused abstract class NIP57Event constructors updated abstract class NIP57Event constructors req'd params amount type from Integer to Long (larger range for millisats) updated serializers

implemented proper RelaysTag/RelaysTags methods removed use of Relay as RelayInfo doc, which is NIP11, not NIP57

removed NIP57Event @NoArgsConstructor as it curcumvents necessary NIP57 parameters added variad constructor to RelaysTag

NIP57 & NIP57Impl updated to accomodate required NIP57 receipt parameters NIP57Event abstract class removed since no useful common attributes between ZapRequestEvent and ZapReceiptEvent

NIP57 createZapRequestEvent unit tests NIP57 createZapReceiptEvent unit tests NIP57Impl ZapRequestEventFactory unit tests