Adds OKToMqtt bool to data

[jp-bennett]

Implements part of https://github.com/meshtastic/rfcs/blob/position-mqtt-privacy/rfcs/2024-08-30-position-privacy.md. This adds a bit to each data protobuf, indicating that the user consents to uploading their data to a public MQTT broker. Without this bit set to true, for the public channel, the firmware will refuse to upload packets to MQTT, and our MQTT broker will refuse to process the packets.

[GUVWAF]

In general I'm okay, but it would thus also mean you have to update your firmware to be uplinked by MQTT gateways that have updated, or if you want to be picked up by the public MQTT?

And we need an accompanying setting for this, which should likely be automatically set when enabling MQTT.
Where do we do the setting? Don't think that the setting needs to be per channel, because only the default key will be picked up by MQTT nodes you don't know. So maybe LoRa config, as it's similar to "ignore MQTT"?

[ianmcorvidae]

This is perhaps nitpicky, but I think we've used snake case usually in protobufs, and this is camelcased (I guess -- acronyms are funny with that, obviously). Probably not super important but nice to stay consistent.

[jp-bennett]

@GUVWAF Yeah, still needs config. And agreed, not per channel.
@ianmcorvidae Yikes, good catch.

[GUVWAF]

it would thus also mean you have to update your firmware to be uplinked by MQTT gateways that have updated, or if you want to be picked up by the public MQTT

This is now not the case anymore, since it's made optional.

[jp-bennett]

it would thus also mean you have to update your firmware to be uplinked by MQTT gateways that have updated, or if you want to be picked up by the public MQTT

This is now not the case anymore, since it's made optional.

My thought is to make it optional for a while, then flip it to blocking by default. Give people time to update, so we don't just nuke the MQTT server overnight.