Send minimal config updates on an established connection

[jaronoff97]

For clients that have modular configurations (collector, bridge, etc.) it would be ideal if the server could send a minimal change update rather than an entire configuration for the client to use. This would keep the wire messages much smaller while also allowing for future policies to be defined about what configuration changes are allowed via the protocol. Similar examples of this can be found in the phoenix liveview spec which allows for a minimal changeset to be sent over the wire to avoid full frontend configuration reloads.

I'm happy to write up the spec change for this proposal.