lxd/config: Allow user keys in server config
lxd/config: Allow user keys in server config

Closes #7870

Signed-off-by: Jared Rankin <c537d686094d67f3f7c280d3e8fcfb7896542165@utexas.edu>

stgraber/lxd,lxc/lxd,hallyn/lxd,hallyn/lxd,atxwebs/lxd,lxc/lxd,stgraber/lxd,hallyn/lxd,hallyn/lxd,atxwebs/lxd,lxc/lxd,atxwebs/lxd,hallyn/lxd,hallyn/lxd,stgraber/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,lxc/lxd,atxwebs/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd