List the active language at the top of the resource manager

When using the resource manager to update your language, you need to search for your language in the list. It's rather cumbersome when you need to do this several times while translating the MuseScore software on Transifex.

A solution would be to list the active language (i.e. the locale in which MuseScore is in) at the top of the list. After all, you may not mind about all the other languages at all.