Investigate loading speakup_soft using udev

[dvzrv]

Hi! Thanks for the recent update to 0.90, which allows me to drop a bunch of downstream integration!

A change I noticed in the .service file is, that it now executes +modprobe speakup_soft via ExecStartPre.
This is an improvement insofar as this (from the downstream point of view) doesn't require e.g. a modules-load.d integration that loads the kernel module during boot and is more dynamic.

However, given that very specific and far reaching capabilities are required to load a kernel module, maybe this can be outsourced to a udev integration instead, that takes care of this on-demand?
This might also allow more service hardening.

[alex19EP]

as far as I know Udev is not intended to load non-hardware drivers at all.

service hardening is possible because exec-pre commands can be executed as root.