The sort orders used to be id_asc / id_desc, and are now created_asc /
created_desc. Users can still have cookies containing the old sort
orders, or bookmarks to links specifying them, so convert these to the
new versions quietly.
Provide more sensible default sort order for issues and merge requests
based on the following table:
| type | state | default sort order |
|----------------|--------|--------------------|
| issues | open | last created |
| issues | closed | last updated |
| issues | all | last created |
| merge requests | open | last created |
| merge requests | merged | last updated |
| merge requests | closed | last updated |
| merge requests | all | last created |