Replace `settings.VERSION` with a set of release data

[jeremystretch]

Proposed Changes

Introduce a canonical module (e.g. netbox/edition.py) containing the relevant metadata for each release, including:

• NetBox edition (Community, Cloud, or Enterprise)
• NetBox version
• Release date
• Beta/experimental designation
• Anything else that seems relevant

This object would replace the VERSION variable currently defined in settings.py.

Justification

This approach enables us to convey more information about each release.