feat(cli): add structured output formatting (-o json/yaml)

[dolliecoder]

What type of PR is this?

/kind feature

What this PR does / why we need it:
This PR introduces structured output formatting to kmeshctl, a highly requested quality-of-life feature for DevOps engineers and CI/CD pipelines.

Currently, kmeshctl commands output data strictly as plain-text tables or strings, making it difficult to parse programmatically. This PR:

1. Adds a global --output (or -o) persistent flag to the root kmeshctl command.
2. Introduces a centralized ctl/utils/printer.go utility to marshal internal Go structs into JSON or YAML seamlessly.
3. Refactors the authz status, log, and secret get commands to natively support structured output via the new printer.

When the -o json or -o yaml flag is omitted, the CLI gracefully falls back to the exact same human-readable table/text formats as before, ensuring 100% backward compatibility.

Which issue(s) this PR fixes:
Fixes #1924

Special notes for your reviewer:
The sigs.k8s.io/yaml and encoding/json libraries are leveraged within printer.go for the struct marshaling. We've ensured that internal data structures (like PodStatus in the authz command) have their fields correctly exported and tagged with json:"" decorators so they serialize cleanly.

Does this PR introduce a user-facing change?:

Added `--output json` and `--output yaml` (or `-o`) flags to `kmeshctl` commands to support structured, machine-readable output formatting.

[kmesh-bot]

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