Change unique device ID to lowest MAC address

[Snuffy2]

• Moves away from the random string generated in OPNsense by the opnsense plugin to the lowest MAC address of the router as the device unique id
• Stores the device unique id which should prevent duplicate devices or entities from being created
  • Still validates in the data that comes back that it comes from the device with the same MAC address before accepting it
• Implements Migrate function to automatically update devices, entities and config_entry.
• Creates both a Minimum Firmware Level where the integration wont install if the firmware is below this and a Limited firmware where it will install but functionality may be limited.
  • Currently min firmware is 24.1 and limited if less than 24.7.
    • Min is 24.1 as the function used to get the MAC addresses from the REST API was first available in 24.1
• Allow deletion of OPNsense Devices only if there are no entities in the Device (this can be expanded later but starting pretty limited for now)

Fixes #215
Fixes #220