It aligns better with the Filesystem Heirarchy Standard[1] to put our
program-specific helper programs that are not intended to be executed by
the user of the application in $prefix/libexec or in whatever the
packager sets as the CMake equivalent. Namely, on Debian systems this
should be /usr/lib/Ladybird or similar.
[1] https://refspecs.linuxfoundation.org/FHS_3.0/fhs-3.0.html#usrlibexec
This will help a lot with developing chromes for different UI frameworks
where we can see which helper classes and processes are really using Qt
vs just using it to get at helper data.
As a bonus, remove Qt dependency from WebDriver.
Re-organize our helper files here a bit, to make a clearer distinction
between Qt-specific helpers and generic non-serenity helpers.
A future commit will move Lagom specific code from LibSQL to ladybird
as well, so that we can see about future generic apis for spawning
helper procesess.
