Add ignoreWarning that takes a RegExp

Like ignoreMessage(QtMsgType type, const QRegularExpression & messagePattern) but for QML.

I would like to provide warning messages that are as specific as possible, but the problem with this is that it makes testing impossible, because if you print out QObject pointers (for example), memory addresses will be part of the output, which breaks the ignoreWarning() call. A RegExp would solve this issue.