Right now, when KRun is invoked to open an `http` or `https` link in a browser, it checks the `BrowserApplication` key in `~/.config/kdeglobals`. If nothing is set there (which is the default), then it introspects the link and figures out for itself what app to open, which has a few quirks and can cause problems (see CCBUG below).
This patch improves the browser discovery logic by additionally looking for a default browser in `~/.config/mimeapps.list`, which is the XDG file and it's where browsers set themselves as the default. So if there is a default browser set in there, KRun will consume that information immediately instead of doing the time-consuming and possibly error-inducing link introspection round-trip.
CCBUG: 347870