Actor groups for samplescan provider

It will be needed to provide different list of actors at different places of the GUI.

As there is a single samplescan provider, one idea is to extend the description with groups or tags

component: samplescan
groups:
   scans_used_at_some_place:
      scans:
         - actor: tomofullfieldscan1
         - actor: tomofullfieldscan2

   scans_used_at_another_place:
      scans:
         - actor: tomofullfieldscan1
         - actor: tomofullfieldscan3

Or using tags (which is closer to the actual language)

component: samplescan
scans:
   - actor: tomofullfieldscan1
     tags:
         - scans_used_at_some_place
         - scans_used_at_another_place
   - actor: tomofullfieldscan2
     tags:
         - scans_used_at_some_place
   - actor: tomofullfieldscan3
     tags:
         - scans_used_at_another_place