nostr-sdk-ios : Add NIP-19 bech32 identifier generation for note, nevent, and naddr prefixes (#166)

* Add NIP-19 bech32 identifier generation for note, nevent, and naddr prefixes

* Apply suggestions from code review

Co-authored-by: Bryan Montz

* Fix incomplete sentence in the Bech32IdentifierType documentation

* Remove unused bech32NoteIdPrefix constant

* Inverse the excludeAuthor and excludeKind parameters in the shareableEventCoordinates function in the ReplaceableEvent protocol for easier readability

* Refactor duplicate code for the shareableEventCoordinates function for ReplaceableEvents

---------

Co-authored-by: Bryan Montz

https://github.com/nostr-sdk/nostr-sdk-ios/commit/02756578af55b9ac7119cdd4d8a1dfd39e15c2c3