Add ReviewOpinion delete functionality to review sidebar (#3565)

hypha/apply/activity/adapters/activity_feed.py

hypha/apply/activity/adapters/base.py

hypha/apply/activity/adapters/slack.py

hypha/apply/activity/migrations/0076_alter_event_type.py

hypha/apply/activity/options.py

...y/funds/templates/funds/includes/review_sidebar_item.html

hypha/apply/review/models.py

...review/templates/review/reviewopinion_confirm_delete.html

hypha/apply/review/urls.py

hypha/apply/review/views.py