enhancement request: trace flag for device_id

[zxdavb]

@ghoti57 it would be useful to be able to deterministically discover the evofw3 dongle's device_id.

My use case include scenarios where users have (or potentially have) more than one gateway, so that I can work out which is which without them having to tell my code that things are so.

I note it would also be useful to have this data even whilst having the device in a read-only mode, so sending a dummy packet is not preferred (and I can't be absolutely sure the packet I'm seeing wasn't from another dongle).

The obvious solution would be a traceflag, or to include this data in the !V response.

[ghoti57]

evofw3 0.7.1 includes a new command !I which reports local device class:id

I can't add it to !V because there's likely to be buffer overflow when working with branches