Copter/Plane/Rover/Tracker: add PilotPi support

[heeplr]

Adds "pilotpi" board to support https://docs.px4.io/main/en/flight_controller/raspberry_pi_pilotpi.html

[rmackay9]

Hi @heeplr,

Thanks for the contribution!

I'm not really qualified to review the changes but I can see that the single commit will need to be broken up into multiple commits with each affecting just a single directory. We've got some info on this in the developer wiki here.

[heeplr]

I'm not really qualified to review the changes but I can see that the single commit will need to be broken up into multiple commits with each affecting just a single directory.

I saw this but I supposed it's meant for adding multiple features to different libraries. With this PR every commit msg would be "add pilotpi support" or "enable xy for pilotpi". Should I still do it although it doesn't really ease review?

[rmackay9]

@heeplr,

It's fine for the commit messages to have similar titles but they should have a different prefix. So I think there should be commits with at least these prefixes:

• "Tools: "
• "AP_BattMonitor: "
• "AP_HAL_Linux: "

[heeplr]

@rmackay9 thank you for clarifying.

I ran git-subsystems-split and it worked like a charm.

[heeplr]

Please consider reviewing GPIO_PilotPi thoroughly. I copied GPIO_Navigator and adapted it to comply with the convention of AUX pins being >= 50 and MainOut pins being >= 101, but I don't really know what I'm doing ;)