Support InitialPreference key in .desktop files for mime handler prioritization on Linux
Currently if no default application has ever been set for a mime type, then GIO appears to choose the first entry listed in mimeinfo.cache for the type. In practice this seems to be the first program installed that associated with the type, although the spec also allows for the list to be randomized at caching time.
There is a partial solution to this problem promoted by KDE, mentioned in the spec here: https://standards.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html#kde-items
Lacking any other configured defaults, this key is used to prioritize handlers, and the highest InitialPreference value is selected.
The purpose of this field and this request is to prevent esoteric handlers from being used when more sensible handlers are available on the system. e.g. for inode/directory we probably want to use some "normal" file browser, instead of something like a MP3 tagger or CVS/SVN client, despite both of those being capable of handling inode/directory URIs.
I personally encountered this issue when using Sublime Text 3 and Lutris on a system without the GNOME DE installed.