Currently, if there are any other apps installed that can open .kra files, and they
have the InitialPreference value set in their .desktop file, they will open .kra
files by default instead of Krita. This is non-ideal.
This patch sets the InitialPreference value in Krita's own .desktop file high
enough that it will always be the default first handler for .kra files.
CCBUG: 337272