Add a method to get nameservers in use

Previously, we processed designate-manage pool show command output
through string manipulations, which was difficult to maintain.

This patch adds a dedicated method for the nameservers.

The method was originally presented in the following patch, which is
currently blocked:
https://review.opendev.org/c/openstack/designate-tempest-plugin/+/944760

Authored-by: Arkady Shtempler <ashtempl@redhat.com>
Change-Id: I168590cd2fe0a0520adae817e3a5871479d27117
Signed-off-by: Omer <oschwart@redhat.com>
1 file changed