What this PR does / why we need it:

• Introduces a new commandArgs parameter that allows complete control over Feast CLI command-line arguments
• Maintains full backward compatibility with existing configurations through fallback logic
• Enables access to all Feast CLI options including previously unavailable ones like --root_path, --registry_ttl_sec, custom ports, and future options
• Provides comprehensive documentation and examples for all Feast deployment modes
  Creates a future-proof solution that doesn't require template updates for new Feast CLI features

The current Feast Helm chart limits configurability by hardcoding CLI arguments. This creates several problems:

• Missing Functionality: Users cannot access many Feast CLI options (e.g., --root_path for UI proxy support, --registry_ttl_sec for registry refresh control)
• Maintenance Burden: Every new Feast CLI option requires template modifications and chart updates
  Inflexibility: Complex deployment scenarios requiring custom argument ordering or conditional options are impossible
• User Workarounds: Forces users to fork charts or use suboptimal configurations

This PR allows for flexible, comprehensive solution that will grow with Feast's capabilities while preserving existing functionality.

Which issue(s) this PR fixes:

None

Misc

None