[gokz-profile] Add "Unknown" rank

[walliski]

Add an "Unknown" rank that could be shown until the ranks have loaded. This makes it clear that the Global API didn't load your rank properly, instead of showing the "New" rank as it is now.

Possibly could cause issues for new players that do not have a profile yet?

Fairly small use case, so probably not worth implementing if it will be a lot of hassle.