Fork detection: Fix Windows naming + add a new check for fork detection

[kalaposfos13]

I saw some screenshots on Discord which had the shadps4-emu/main text instead of just main in the window title, and I think this might be due to Windows handling Git remote links slightly differently, so I changed the code to first extract the name, and then check only that, instead of the full link. I don't actually know if this will fix the issue, but I certainly hope it will.

I also found a possible reason as to why @StevenMiller123's local builds fail to find the remote link even though his push defaults were set, and it is now included as the second thing to check if the branch doesn't explicitly have a remote pair defined.