This allows booting a new image from a running OS, creating a
phram mtd for the root squashfs
* enable CONFIG_KEXEC
* add modules/kexecboot
* patch kexec-tools to add --map-file option for the squashfs
* patch kernel kexec code to call new kernel with DTB
- dropbear
- generate host keys on first use
- mount /dev/pts
It's not ideal having the host key disappear when the device is
reboot, but without persistent storage the alternative is generating
it at build time. Deferring this problem to another time
This is a hefty change
* add support for kernel backports project
* build wireless stack/drivers as modules from a backported kernel
* create a service to load/unload the modules
by having two separate derivations for patching the kernel source tree
and building it, we have to copy said source trees from one store
location to another which takes non-neglible time on spinning rust
(literally minutes on my machine). Replace with a single derivation
that can do more things on one tree in-place
would be good to move more of this into a module, but that
doesn't sit well with the (potential) ability to run more than one
dnsmasq service, as modules are singletons
