[amd64, arm64] Add d-i support for UEFI and U-Boot HTTP boot

UEFI HTTP boot and the U-Boot equivalent work by making the installation media available as /dev/pmem0. In order for the installer to be able to mount it, we need to have pmem modules in the installer initrd. Currently, if the installer is started via HTTP boot it fails to detect installation media.

https://github.com/tianocore/tianocore.github.io/wiki/HTTP-Boot https://www.linaro.org/blog/ledge-blogs-uefi-http-and-https-boot-in-u-boot/

Related bug: #879106