Add a 'ready_for_testing' property to NSC

On exchange_lan NSC creation, LINX requires the member to tell us when they are ready to begin quarantine testing, this ensures we do not send test traffic before their hardware is configured and ready.

To support this via automation, we need to allow the member to PATCH their NSC via a property that tells us they are ready.

To ensure this is kept generic on the schema, we would like to propose an optional, boolean property called something like:

• ready_for_automated_testing
• technical_service_configured
• nsc_testing_initiate

By default this value for LINX would return false and once updated by the member we would action the testing.

For those IX that do not support this, the property would be omitted from their response.