tristate features will automatically disable if dependencies marked
as required are missing.
Packagers can manually override using `auto_features`.
Link: https://mesonbuild.com/Build-options.html#features
There's no actual hardware to test this against yet, but this is how I
would lay out a plugin if there was.
We still need to work out a generic encapsulation for the offer and
payload (for each component and bank) so this can work with LVFS and
fwupd.
