virsh: Adjustments for the VIRSH_COMMON_OPT_POOL

virsh: Adjustments for the VIRSH_COMMON_OPT_POOL

The macro is slightly adjusted to add an argument "_helpstr". This
will be passed as a translation macro string since other uses of the
option may not have the same exact help string (such as is the case
when the uuid is not suppliable for create commands).

In virsh-pool.c - we'll create a singular VIRSH_COMMON_OPT_POOL_FULL
in order to pass along the 'N_("pool name or uuid")'

In virsh-volume.c there will be a VIRSH_COMMON_OPT_POOL_FULL and a
VIRSH_COMMON_OPT_POOL_NAME, which passes 'N_("pool name")' for
the commands that can only pass a name. There will also be a
VIRSH_COMMON_OPT_POOL_OPTIONAL which is used for the command
options which use OT_STRING and don't require the --pool argument.

Signed-off-by: John Ferlan <jferlan@redhat.com>