Allow users to hide challenges

Is your feature request related to a problem? Please describe.

Trying to view area for challenges results in being flooded by challenges of no interest and no way to hide it.

For example https://maproulette.org/browse/challenges?challengeSearch=19.9258303642273%2C50.052413263334984%2C19.95552778244019%2C50.06358566357687&location=intersectingMapBounds has https://maproulette.org/browse/challenges/37282 which is no really bad - in theory you can try to check online presence of museums.

But for me it is of zero interest, I strictly prefer to solve this by answering StreetComplete quests with less web page crawling and more walking, and with higher success rate.

And bunch of "add localisation" challenges that I cannot process at all as I do not speak Turkish for example.

This crowds out any potentially interesting things that I would want to see.

Describe the solution you'd like
Ability to do exact opposite of favorite: to hide challenge from various listings.

Describe alternatives you've considered
Do not try to use places listing challenges.

Additional context

Maybe, maybe it could be one of indicators to find preferred challenges to show to people (prefer ones with favorites, without ignores)

Start by locating the challenge listings and the existing favorite control in the frontend. Trace how challenge visibility and listing filters are handled, then define the hide action and verify that hidden challenges no longer appear in the relevant listings while favorites continue to work.