kubectl-like get command for mgrctl

My goal is to fix this by implementing mgrctl get a simple, kubectl-style interface for querying Uyuni resources. Think mgrctl get systems, mgrctl get errata --cve CVE-2026-1234, or mgrctl get jobs --state failed. Everything goes through the existing Uyuni REST API, so there's no new authentication logic to worry about, and the output can be a clean table, JSON, or YAML depending on what you need. By the end of the program I plan to have full coverage across five namespaces like systems, system groups, channels, scheduled jobs, and errata , with filters, structured output, and a mock-based test suite that doesn't need a live Uyuni instance to run. If time allows, I'd also like to add mgrctl describe for richer single-resource views and shell completion for bash and zsh.