New features and bug fixes on Netbox 4

[leomarssilva]

I've added code for some changes I've found on Netbox v4.

New features:

• Disk initializers for virtual machines
• OOB IPs for devices
• Optional associations to device_types.py and locations.py
• Multiple content type support for custom links

Fixes:

• Cable routing on Netbox v4
• Change "ui_visibility" on custom fields to match the name field on Netbox v4
• Fix custom fields to work with "object" and "multiobject" types
• Empty fields on custom fields after setting the "on_objects" association
• Zeroed CounterCacheField values on devices.py when we set custom fields or tags

Let me know if you have any questions or need me to change something :)

[tobiasge]

Are those changes intended for Netbox 4.0.x or 4.1.x?
The min and max versions should need to be set accordingly.

[leomarssilva]

I'm using Netbox 4.0.x, but they should work also for 4.1-beta