Reconcile/merge devices.

Similar to #537, I have devices that sometimes (but not always?) fail to discover the DeviceID despite having the same mac address (Private mac address is disabled.)

This makes the nextDNS logs fairly unusable. It would be amazing if a "clean up" feature was added so that:

1. Devices IDs (names) could be edited (renamed when the entire name doesn't come through properly)
2. Merged when the same device appears more than once, the data could be merged into a single entity. This would allow users to manually fix when auto-discovery fails for whatever reason.