13745 device type migration

[arthanson]

Fixes: #13745

Optimize counter field migration on DeviceType for large databases.

[jeremystretch]

While this addresses the immediate concern, I'd argue that we should utilize the same approach for all three affected migrations (dcim.0176_device_component_counters and virtualization.0035_virtualmachine_interface_count as well).

Also, we probably want to move the logic from the management command (rather than duplicating it) somewhere internally so that it be can be reused by the migrations.

[arthanson]

While this addresses the immediate concern, I'd argue that we should utilize the same approach for all three affected migrations (dcim.0176_device_component_counters and virtualization.0035_virtualmachine_interface_count as well).

Also, we probably want to move the logic from the management command (rather than duplicating it) somewhere internally so that it be can be reused by the migrations.

Moved the calculate routine to utilities then updated all migrations to use this pattern.