device-generic-x86_64: add oem-specific subpackages
Note: testing this currently requires these patches to pmbootstrap: https://lists.sr.ht/~postmarketos/pmbootstrap-devel/patches/48226
This uses oem-specific packages for configuring Intel and AMD systems, and installs them all by default for new images using pmbootstrap's pmb_recommends feature.
The intention is to provide pre-built images with support for Intel and
AMD already enabled/configured, and users can remove an unwanted set of
packages (e.g., apk del device-generic-x86_64-intel when on an AMD
system) if they want to.
Upgrading existing systems should work, in that I haven't observed any
apk conflicts with it. But you do need to manually install the new
oem-specific package if you need it (e.g. oem-intel)
fixes #2484 (closed)
cc @jenneron, you helped with the idea for this design, and I'd like your feedback on how it's implemented here since we'll probably want to do something like this in other "generic" device packages?
cc @ollieparanoid on the new use of pmb_recommends (and the pmb patches, which I'll submit to the mailing list once I have some more feedback that this is on the right track 
