Detect if internet connection is through a carrier grade NAT (starlink)

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Users who have starlink internet (as well as many mobile networks) are not able to have reliable connectivity because these services use a CGNAT and constantly have their external ip address changing. The sdk can detect this by checking the interface address against the `CARRIER_GRADE_NAT_SUBNET` ip range. This can be used to disable blob announcement where it won't be effective and to alert the user that they can't be connected to from the outside.

Detection of the CGNAT might be trickier on starlink connections with a wifi network (the default they ship with, vs ethernet with passthrough) as the interface address will appear to be a normal private lan address. I'm not sure if the wifi router will reply to aioupnp - if it does it probably gives the CGNAT address (this can be tested).

Start by locating the interface-address handling, the CARRIER_GRADE_NAT_SUBNET check, and any aioupnp integration. Verify how Starlink Wi-Fi and ethernet passthrough expose addresses, then make CGNAT detection available for disabling blob announcement and alerting users that inbound connectivity is unavailable.

Written by the indexing model from the issue text.