Add deactivate step to extend_lv

Add deactivate step to extend_lv

Extending a linear LVM volume that has a snapshot requires
that the LV be deactivated explicitly prior to extending.

This adds a deactivate_lv method and calls it prior to
issuing the extend call. If auto_activation_volume_list
is not defined lvm.conf, then volumes will be reactivated
automatically after the extend.  If auto_activation_volume_list
is defined, then volumes that should be automatically
reactivated should be added to the auto_activation_volume_list
or they won't be activated automatically.
NOTE: This doesn't apply to thin provisioned LVs as they don't
require the deactivation step.

DocImpact: When a user extends LVM Volumes with a snapshot, the
volumes will be deactivated.  Their re-activation is automatic,
unless auto_activation_volume_list is defined in lvm.conf.
See lvm.conf for more info.  Thin provisioned LVM Volumes
will not be deactivated as they don't require it.

Co-Authored-By: John Griffith <john.griffith8@gmail.com>
Change-Id: If746625cfe658c3528525dc7f4bf869f1c9704dc
Closes-Bug: #1470558