use default app for external apps when not specifying one

[wkloucek]

Bug description

web/packages/web-app-files/src/mixins/fileActions.js

Lines 142 to 150 in bdd7075

	// TODO: Make user-configurable what is a defaultAction for a filetype/mimetype
	// returns the _first_ action from actions array which we now construct from
	// available mime-types coming from the app-provider and existing actions
	$_fileActions_triggerDefaultAction(resource) {
	const actions = this.$_fileActions_getAllAvailableActions(resource).filter(
	(action) => action.canBeDefault
	)
	actions[0].handler(resource, actions[0].handlerData)
	},

If a user clicks on a file, which can be opened by multiple external apps, it will be opened with the first one in the internal array. This is quite random to a user and false in the sense, that oCIS knows about default apps (configurable by an admin atm).

Opening a file with the default app is done by calling /app/open without a app_name query parameter.
Additionally we also could add this information on the /app/list endpoint, which application is the default, if this is helpful to you.

Originally posted by @wkloucek in #5805 (comment)

[kulmann]

Good one. And an easy fix: if at least one app for a mimetype: call /app/open, if no app available for the mimetype: don't use the app provider.

If think we don't need the default info in the /app/list endpoint, but sorting or an app weight/prio would be helpful. I think there was another ticket about that, right?