When using impersonation user information and permissions not preserved when switching context

[BenediktFloeser]

Describe the bug
When using impersonation via the --as option the authentication information is apparently not carried over when switching context. As best I can tell k9s seems to fall back to my default user when switching context.

To Reproduce
Steps to reproduce the behavior:

1. Set up two contexts/clusters
2. Set up two users in both
3. Give user-1 edit permissions for context-1 and view permissions in context-2
4. Give user-2 permissions to impersonate user-1 and view access
5. Start k9s with k9s --context context-2 --as user1 as user-2
6. Switch context to context-1
7. Try to edit a resource user-1 has permissions for

Expected behavior
When switching context, I expect the active user and its permissions to be preserved.

Versions (please complete the following information):

• OS: Fedora Workstation
• K9s: 0.32.6
• K8s: 1.30.5