Update CLI to manage multiple user sessions

[dborovcanin]

          CLI suggestion: (This can be done in separate PR)

We can add context management to the CLI, allowing users to manage multiple sessions with domain_id and token.

Users can:
Add a context with mg-cli add-context <DomainID> <token> <contextName>
List all contexts using mg-cli list-context
Switch contexts with mg-cli use-context <contextName>

This setup helps manage multiple sessions seamlessly.

LGTM

Originally posted by @arvindh123 in #2468 (review)