feat: add metadata-service commands

[synackd]

Description

Add commands that map to the metadata-service API to support interacting with metadata-service through ochami.

Metadata-service commands are all under the metadata top-level command, aliased as md:

• ochami metadata defaults: handles cluster defaults
• ochami metadata group: handles cloud-init group templates
• ochami metadata instance: handles instance info records
• ochami metadata peer: handles WireGuard peer records
• ochami metadata service: handles metadata-service status checks

The defaults, group, instance, and peer commands contain add (create), delete, get, list, patch, and set (update) commands. The service command currently contains status.

This also adds metadata-service client wrappers, configuration support for metadata-service service URIs and API versions, and the ochami-metadata(1) manual page. add commands support both single-object and array payloads, with JSON and YAML examples documented in command help and the manual page.

Token handling is enabled and follows the existing ochami service command conventions.

Checklist for Reviewers

• Verify ochami-metadata(1) manual page is accurate and descriptive
  • make man, man ./ochami-metadata.1
• Verify ochami metadata <cmd>... --help output is accurate, including examples
• Verify defaults/group/instance/peer commands accurately and predictably manage their respective resources for each of the subcommand actions.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update