mediacontrollertest: test touch gestures, multiplexer and integration with Plasma Browser Integration

applets/mediacontroller: test touch gestures

This adds a touch gesture test to make sure the media controller widget can react to touch gestures correctly.

applets/mediacontroller: test multiplexer

The multiplexer should be hidden when there is only 1 player, and shows information from the active/playing player if there is one.

applets/mediacontroller: test browser instance is filtered out

When Plasma Browser Integration is installed, the widget should only show the player from p-b-i, and hide the player from the browser.

test

Closes #92 (closed)

Ref: teams/automation/issues#9 (closed)