Add support for RSSI in dBm and LQ to GHST

[tonycake]

Extend the GHST driver to provide RSSI in dBm and LQ using the mechanism recently added to other PX4 RC drivers.
These values were already provided in the GHST telemetry stream, but only the (limited value) RSSI in % was previously available.

[dagar]

Did you see the CI build and format failures?

[tonycake]

Did you see the CI build and format failures?

Yes... n00b mistake :-(

[tonycake]

Did you see the CI build and format failures?

Fixed the formatting, and squashed the commits. Flash error during CI is a little confusing, any advice?

[mrpollo]

@tonycake can you please rebase your branch with the latest from upstream main? we pushed a fix that should take care of the failing CI test

[tonycake]

@tonycake can you please rebase your branch with the latest from upstream main? we pushed a fix that should take care of the failing CI test

Wondering how to get this PR merged. The check related to flash usage is not exactly clear, and seems to indicate a problem unrelated to my change.
Any advice would be great.

[dakejahl]

@tonycake rebase again and it will pass. We've disabled that check since.