Add protocol and API for determining metaverse that the domain server is using

[ctrlaltdavid]

If the user (app + SDK) logs into one metaverse but the domain server is using a different metaverse then things won't work.

Perhaps add a packet or pair of packets.
Perhaps add in DomainSettingsRequest and DomainSettings packet pair - esp. if metaverse server is specified in domain server settings.

Can't add the metaverse URL to just the DomainList packet because this may not be sent if the user isn't authenticated on the domain.