Refactor and re-focus to device-type functionalities

Ping protocol has been fragmented into including message sets for several independent devices, instead of the more generalisable approach of supporting broad device types. This makes it needlessly difficult to test expanded/modified functionalities, both from custom firmware and custom hardware.

I think we should make a v2 of the protocol which primarily uses device type message sets, with inheritance as relevant (e.g. common -> single transducer -> hydrophone / beacon / echosounder / scanning sonar / ...), and broader messages that are not prescriptive to hardware implementation details.

There can then be a separate "implementations" section which lays out specific known restrictions for individual device firmware options (e.g. a table of which device firmware supports which messages, and the value limits it supports within those messages, like the Ping Sonar proprietary firmware range and gain limits).