In the list of challenges, add indicators if a current user has joined/completed that challenge

[karina-klinkeviciute]

CONSIDERATIONS:
As some challenges can be completed more than once, I am not sure how to visually implement this. Might be checkmark if completed, but also some other if there are ongoing ones?

There is a field can_be_joined on the challenge. Users can't join challenges which they already joined/completed that are marked as doable only once.

There is also is_joined which is true if the challenge is currently joined at least once (but not if completed).

If a challenge has been joined, but not completed (is_joined is true) it should have a green checkmark indicator next to it. It means it can be continued (completed).

If a challenge can't be joined or continued, it should be greyed out and unavailable for joining but should be still showing.