Feature Request: Using proposed algorithm tags for filtering tasks.

[segir187]

Feature meant to make it easier for users of platforms like Szkopuł to find tasks with few or none admin-given tags, when searching for tasks using a chosen algorithm.

As of now, as far as I'm aware, the proposed tasks are only visible to admins and the only way for users to interact with them is by proposing tags for a task. This would make better use of them.

Note: implementing this makes sense only after the implementation of issue #419.