Clarity on the use of Friendly name

[backkem]

The current Chromium implementation requires a friendly name as represented by a "fn" mDNS txt record.

I wanted to confirm if:

1. Is this a remnant from google cast and a requirement we want to remove, as the OSP spec covers this by the instance name and the display name in the metadata discovery.
2. There is still some merit to having a friendly name and we need, so we'll update the OSP spec accordingly.

[wangw-1991]

I think the biggest difference between friendly name and instance name is that: instance name should be unique and mDNS conflict resolution procedure is used to guarantee it (in current chromuim, if an instance name is already used, a sequence number will be added to the instance name to form a new instance name), while friendly name doesn't have to be unique.