Add PINIO 3 & 4 plus MATEKF722PX_PINIO target

[MrD-RC]

There are plenty of flight controllers around now that use PINIO 1 and 2 internally for camera switching and switchable VTx power. This left no scope for user definable PINIO. A friend wanted to control a Caddx Peanut on such an FC. So I have implemented USER 3 and USER 4 PINIO options. Also in the PR is the target that was created for my friend. Said target works like a charm.

When rebasing to 6.0 master, I initially worked on 5.1.0 base, I saw that shellixyz had added USER 3 to master. But It had a box mode ID conflict. I fixed the initial problems with PR #8276, which negates the need for fixes #8346 and #8394. As USER 3 is not yet in a release (no milestone), changing the box ID for that makes the most sense. Due to this, no current box modes are disrupted at all. All diffs will work fine from 5.x to 6.x as far as box modes are concerned.

This will require a small Configurator update to correct the ordering on the modes page and add support for the LCs. https://github.com/iNavFlight/inav-configurator/pull/1621