Add `git describe` output to file_basename and build.cpp

[bs-github]

• By adding the output of git describe we get a clear view on what git commit we are building on. This way investigating error reports even on intermediate builds is more easy.
• This change inserts the following to the filename of the firmware, as well as into the build.cpp to add a log line on boot.

warpAC011K_firmware_2_0_11_63e7c626_  
warpAC011K-2.0.8-186-g34455a3d-improve-build-versioning-2023-02-11-17:45:26  
_merged.bin

• most recent tag, and if there are further commits, the:
• number of commits thereafter, as well as the:
• git commit hash, and if the build is not clean, the:
• name of the current branch, and the current:
• date time

This addresses #24