use DJI FPV OSD element CRAFT_NAME to show warnings and more

[mf0o]

DJI FPV only supports a limited set of OSD items today.
Missing the iNav warnings is very annoying and probably the most critical at the same time.

This feature branch can use the CRAFT_NAME OSD field to show warnings, throttle position, trip distance, 3D speed and efficiency (mAh/KM).
The field CRAFT_NAME inside DJI is limited to 10 characters.
Various functions have been ported and renamed from osd.c to remove symbols and shorten messages.
Not using a new parameter for configuration is intended, to reduce the footprint within iNav if DJI adds features in the future.

summary:

• configuration can be done through the craft name itself
• feature gets enabled if the name starts with ":"
  • if name does not start with ":" the craft name will be simply shown
• each configurable elements is represented by 1 capital letter like:
  • (W)arnings, trip (D)istance, 3D (S)peed, (T)hrottle, (E)fficiency
• to use warnings, W must be the first character (but it is optional)
• order of the elements will be preserved, valid examples:
  • set name=:W
  • set name=:WTDES
  • set name=:WEDS
  • set name=:WSE
  • set name=:ES
• if warnings are present, it will override the other elements
• each non-warning element will iterate for 3 seconds
• if only warnings is enabled but none present, nothing will be displayed - DJI by default shows CRAFT_NAME if no name is supplied
• invalid characters will be handled and shown as UNKOWN_ELEM

appendix:

I captured an example from the goggles screens: screen_grab
inav/issues/5945

[mf0o]

Oh, seems that I've created the PR from branch release_2.5.2 and not from master.
Sorry for any trouble caused, first time contributing. There is actually only 1 file changed, Im gonna close this and do another

[mf0o]

RTFM, took the wrong branch before creating the pull request

[Schalonsus]

Please add aircraft heading value