* Extract BitchatMessage into a separate file
* Convert `fromBinaryPayload` to `convenience init?`
* Extract message dedup into an extension
* Remove dead `formatMessageContent`
* Minor refactor of timestamp and username formatting
* Remove dead `getSenderColor`
* Extract MessagePadding into a separate file
* Extract BitchatPacket into a separate file
* Extract ReadReceipt into a separate file
* Extract NoisePayload into a separate file
* Remove unnecessary import
