update lease when device moves to different network

[BeryJu]

closes #762

Previously, when a device moved to a different network while keeping the same identifier, it would get the same lease it did before, even if that lease was not in the new scope the device is now in.

This adds a check to ensure that before a lease is returned, it must be in the same scope that would be picked for a new device. If that isn't the case, the lease is updated to use the new scope, and gets a new address assigned. All other options of the lease are kept as they were, including expiry and reservation status

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[codecov]

Codecov Report

Attention: 13 lines in your changes are missing coverage. Please review.

Comparison is base (1201df8) 58.89% compared to head (96d84bf) 57.64%.
Report is 3 commits behind head on main.

Files	Patch %	Lines
pkg/roles/dhcp/leases.go	64.86%	9 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #777      +/-   ##
==========================================
- Coverage   58.89%   57.64%   -1.26%     
==========================================
  Files         106       89      -17     
  Lines        5873     4571    -1302     
==========================================
- Hits         3459     2635     -824     
+ Misses       2082     1665     -417     
+ Partials      332      271      -61     

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