SPDX Support in Dunfell

Joshua Watt

There has been a strong desire to have our SPDX support in the Dunfell
LTS release. As such, I've put together a patch series in poky-contrib
to try this out, which can be found here:

If you have already gone through the exercise of backporting this on
your own (currently, I only know of Paul doing this), it would be
really helpful if you could give this a try quickly and making sure it
will work for you. I'm going to clean up the commit messages on these
patches and hopefully submit them to the mailing list to be merged

It is mostly identical to the version that currently exists on the
master branch with the major exception that is uses gzip instead of
zstd for compression. This change was made to prevent the need to
install zstd on some of the older host distros that dunfell supports.

Joshua Watt