kernel: Chart out future for kmod-kit

[foersleo]

kmod-kit currently does not support cross compiling external kmods for other architectures, like we do for our general package builds. If we do not want to build kmods on the target instance, but check building for all target architectures (x86_64 and aarch64 currently supported for aws variants) we need two separate builder hosts. Check our options for kmod-kit supporting cross compilation of modules.

Another possible answer might be, that kmod-kit might not be the best way to add custom kernel modules once we have support for out-of-tree builds. Once that feature lands, it might be easier to create an out-of-tree variant with the necessary modules instead of going through fetching kmod-kit, building modules and distributing it.

The idea for this came up during discussions around the 6.1 kernel enablement: https://github.com/bottlerocket-os/bottlerocket/pull/3121