[pve-devel] fix #5254: add separate Sys.AccessNetwork privilege

[Thomas Lamprecht]

What I forgot to mention:

- docs patch is still missing, but would just add an entry for this new priv
  in the list of existing privileges with a short description

- there aren't really hard dependencies between the patches of the different
  packages, it just won't work, so I do not think we need to actually bump
  the d/control package dependency versions for just this.