Device-implemented Settings fields

[calvinleng-science]

Summary

The old specification for settings was rather SciFi-specific. It assumed the notion of name, time source, and FPGA clock frequency were valid notions for all Synapse devices, which could be true, but it could also just be generalized. This generalization will likely especially be appreciated once we implement PRIMA as a Synapse device.

This change makes settings defined by the device with the schema for each field returned as part of the GetSettingsResponse.

Changes

• Removed "name", "time_source", and "fpga_clock_freq_hz" and reserved them to prevent future use of these fields in the case of new client implementations making requests to outdated server implementations
• Added SettingDescriptor to hold information on a setting's fields' schemas
• Updated GetSettingResponse to return the schemas

Testing

• SciFi implementation: https://github.com/sciencecorp/headstage/commit/e22cb072ead459e4457913e63cfc92c730ac0e8d
• synapse-python implementation: sciencecorp/synapse-python@a5f9c78
• synapse-typescript: shouldn't need changes outside of pinning to newer version of synapse-api, just a thin layer
• nexus-desktop: https://github.com/sciencecorp/nexus-desktop/commit/8f5064073129eb07ba6a772e3315d753475dc734

^ synapsectl showing all the fields registered by scifi-server in headstage. Registered a "hello_world" field to 100% guarantee that clients do not need to be aware of the fields at "compile time".

Note that up-to-date clients asking out-of-date SciFis will show that the SciFi has no settings. People will need to update their SciFis. I can make the clients backwards compatible, but that will be a little ugly: will either have to keep the old fields in DeviceSettings, or will have to put legacy protos in all of our clients.

[namthor9]

Approved, good change