[Tools] Implement all the cta-admin commands with gRPC

Description

This commit implements all the cta-admin commands with gRPC as the transport. Authentication will be handled in a follow-up merge request.

Checklist

• Documentation reflects the changes made.
• Merge Request title is clear, concise, and suitable as a changelog entry. See our contributing docs

Additional Required Actions

• Requires manual tests in pre-production: YES/NO
• Requires a documentation update: YES/NO

References

Closes #338 (closed), #339 (closed)