-fixes #4745

-fixes #4828

This brings various PRs in:
- RPi build fixes
- unit tests on CI and on Mac
- some cmake cleanup
- CI style check for DF

By running the loop in mc_pos_control without successfully polling on
position data, we still copy the manual input over so that
mc_att_control can consume it. This allows to fly in manual mode without
GPS and no position estimate.

Previously sdlog2 got stuck in an endless loop if an unknown argument was
given

This lead to a segfault, for example 'logger start -r'

20 Hz of RC_CHANNELS makes the RC calibration in QGC a more pleasant
thing.

look for alternate topic list at
/fs/microsd/etc/logging/logger_topics.txt
on and off commands have the same effect as arm/disarm

Previously, if no time was set, sdlog2 created a folder like sess001,
sess002 for every logfile. The logfiles would then always be named
log001.px4log and their numbering would not actually increase.

This is now fixed and a new folder is only created per boot.

Change prefix construction to allow correct building of scope tag in parameters.xml when building out-of-tree (#4781)

Fixes issue #4767

Namely the following output after Ctrl-C:
Invalid command: muorb
type 'help' for a list of commands