feature: Allow quickly reading Axii's config

• Allows quickly reading Axii's config with the dedicated command _axii_fast_config. It can even be further sped up by installing jq (JSON command line parser) via apt.
• Reworks axii init.
  • Extract I/O code from core module, and move into cli module.
  • Suggest using axii config global default_config <workspace name> (shell agnostic) instead of sourcing workspace rc files in the basrc.
  • Allow using axii init with command-line flags in a non-interaction manner.
• Overhaul CLI documentation.