The header doesn't yet include the SetThreadDescription() definition but
it is in the UCRT library so ship own declaration of the function for
now.

- pass generated data with testcard_state2::data variable + notify with
  CV to thread that it is available
- use dispose to "automatically" manage grabbed frames

+ fixed leaked text surface

Take it as a dependency

av_frame_wrapper_recycle() and av_frame_wrapper_copy() moved from header
to rpi4_out.cpp.

- do not print device modes + connections - usually not needed because
  there is signal autodetection with recent DeckLink cards and user
  usually knows the connection directly
- print available color space more dense

The outcome is that the output fits (usually) one screen while avoiding
unnecessary items (but print all possible connections).

Those were useless and caused some undefined references in Arch Linux:
https://bugs.archlinux.org/task/70286

+ check for opencv_imgproc that is usually also required

The test failed failed when width % 2 == 1, which wasn not handled
properly by the conversion function.

for Coverity checks that are without it

+ do not require testcard2 for audio/mixer for testcard (1)

The conversion between UYVY and YUYV is symmetric so the same function
can be used.

Use testcard_convert_buffer() for pixel format conversion to avoid messy
code that there has been.

+ removed redundant functinos
+ relicense (there remains nothing from original code now)

tv_add_usec fixes handling of 2^31 us addition overflow and the original
function, tv_add is not slower if tv_add_usec is inlined.

+ improved a bit

as it is currently in the AppImage

Copy DejaVu Sans+Mono Book+Bold explicitly + pass it a variable
UG_FONT_DIR to UltraGrid.

Ensure that DejaVu fonts are installed since create_appimage.sh expects
those fonts to be present.

Changed font location to <appimage>/usr/share/fonts - this is more
convenient location than <appimage>/usr/lib/fonts.

Disable also all other components except XiApi.

Component names decompiled from installer with 7-zip 15.05, see also
https://nsis.sourceforge.io/Can_I_decompile_an_existing_installer.