Ensures we remove the solution when the post marked as the solution is deleted.
DEV: Added `IS_ACCEPTED_ANSWER_CUSTOM_FIELD` constant.
DEV: Refactored the `PostSerializer` for better readability.
PERF: Improved the `TopicViewSerializer`'s performance by looking up the `accepted_answer_post_info` from the stream first.
Internal ref. dev/112251
`allow_accepted_answer` should be `allow_accepted_answers` (with an `s` at the end) in the `TopicAnswerMixin`.
The `enable_solved_tags` setting description seemed to be using the description intended for `allow_solved_on_all_topics`. Both descriptions have been updated.
This PR adds a site setting called `enable_solved_tags`. Solved will be enabled for topics containing these tags, just like we do for specific categories.