Remove notification question code

Background

We're removing the anti-adblock warning notifications with https://gitlab.com/eyeo/adblockplus/abpui/adblockplusui/issues/43 and the corresponding platform code with eyeo/adblockplus/adblockpluschrome#99 (closed). Once those are both finished, we can also remove some core code.

What to change

• Remove notifications.triggerQuestionListeners, notifications.addQuestionListener and notifications.removeQuestionListener.
• Remove url filtering logic from _getNextToShow.
• Remove/adjust tests for notifications with question type or url filters.

Integration notes

• No longer pass the url parameter to notifications.showNext().
• No longer create notifications with the "question" type.

Hints for testers

We've removed support for question notifications and notifications which only apply to specific pages. Please test that notifications otherwise work as before.

/cc @ThomasGreiner