* virsh-domain-monitor.c: Add domMonitoringCmds
* virsh-domain.c: Add domManagementCmds
* virsh-host.c: Add hostAndHypervisorCmds
* virsh-interface.c: Add ifaceCmds
* virsh-network.c: Add networkCmds
* virsh-nodedev.c: Add nodedevCmds
* virsh-nwfilter.c: Add nwfilterCmds
* virsh-pool.c: Add storagePoolCmds
* virsh-secret.c: Add secretCmds
* virsh-snapshot.c: Add snapshotCmds
* virsh-volume.c: Add storageVolCmds
* virsh.c: Remove all the above *Cmds.

Commands to manage secret are moved from virsh.c to virsh-secret.c,
with a few helpers for secret command use.

* virsh.c: Remove secret commands and a few helpers.
           (vshCommandOptSecret, and vshCommandOptSecretBy)
* virsh-secret.c: New file, filled with secret commands and its helpers.
* po/POTFILES.in: Add virsh-secret.c
* cfg.mk: Skip to check config.h including for virsh-secret.c