Fixes playing recordings on Windows

**FIX!**

It turned out that on the Windows platform, names of recordings were still passed as UNC share names. This causes the built-in player to fail in Gotham.

Now all UNC share name versus CIFS name handling is isolated into just two methods, and the addon internally always works with CIFS names (smb://....).

This actually strips a lot of code, making the addon code easier to follow, and hopefully more robust.