[Enhancement] Make switching namespaces/instances easier

[bluesliverx]

Currently we are managing secrets across 2 different vault instances and 2 different namespaces. That makes a lot of logging out and logging back in continually with the other namespace (manually typing it in each time). I would like to see the namespace be combined with the saved endpoints so you can just select something like:

• vault1.com (no namespace)
• vault1.com (my-namespace)
• vault2.com (my-namespace)
• etc...

It would also make it a lot easier if we could run multiple cryptr's at a time, but that's probably outside of the scope of this. I'm happy to help out with adding this functionality if you gave me some pointers on development.