This PR adds reactions for tasks and comments, similar to what you can do on Gitea, GitHub, Slack and plenty of other tools.
Reviewed-on: https://kolaente.dev/vikunja/vikunja/pulls/2196
Co-authored-by: kolaente <k@knt.li>
Co-committed-by: kolaente <k@knt.li>
When adding a new task relation, the task search input would previously show all tasks in a seemingly random order, including done tasks. Usually, you don't care about these done tasks when adding relations. This change modifies the sort order so that done tasks show up last in the search results.
