Inform user about changes

[mxmehl]

Fixes #63

This PR replaces the INFO output and provides an overview of all changes at the end.

Output format can be controlled by --output. Available choices are json and text.

Additionally, the logging level is WARNING by default now. -v and -vv (also the existing --debug) can be used to control this.

Example:

#--------------------------------------------------------
# Changes made to GitHub organisation OpenRailAssociation
#--------------------------------------------------------

⚠️ Dry-run mode, no changes executed

⚠️ Members without team: EthanPERRUZZA

🤝 Team Changes:
  🔹 Authentik User Manager:
    🆕 Has been created
  🔹 Compliance Assistant:
    🔧 Changed config:
      - Setting 'description': 'Maintainers of https://github.com/OpenRailAssociation/compliance-assistant' --> 'Maintainers of https://github.com/OpenRailAssociation/compliance-assistant and related repos'
  🔹 OSRD:
    ⏳ Pending members:
      - victorlenel

📂 Repository Changes:
  🔹 purl-tools:
    🔧 Changed permissions for teams:
      - Compliance Assistant: maintain
  🔹 authentik-user-manager:
    🔧 Changed permissions for teams:
      - Authentik User Manager: maintain