shell: add trackbone wrapper to limit local evaluation time

The wrapper will look at the arguments passed to trackbone and if the user target specific zones with the -z option this list of zones is set in envs-ng with the targeted_zones tag.

Based on this tag we limit the number of zones coming from caascad-zones to be imported in envs-ng.

This makes the evaluation much faster when targeting one or a few zones.

If not specific zone is targeted (like in the CI), then all zones are targeted like before.

 time cue eval -t targeted_zones=ocb-demo >/dev/null

real    0m4.521s
user    0m7.064s
sys     0m0.113s

 time cue eval >/dev/null

real    0m31.025s
user    0m56.580s
sys     0m1.238s