Add unit testing for QtOutputFormatter

Mainly adds infrastructure to be able to test the matchLine, handleLink
methods.

Change-Id: I70aa2f84b520ad7c0cf84369afcf7bb8f7efab85
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>
Detect QML runtime errors starting with 'qrc:/' too

Change 7c7d26da8b856 added support for qrc:///, but not qrc:/.

Task-number: QTCREATORBUG-11475
Change-Id: I8e75d26462fdf9fa216e6295de4341edcb430fb5
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>