Some improvements to the member list

[ddabble]

Proposed changes

New features

• Added links to the guides on what should be done when a member enrolls/retires/quits, in the member list (711430d6c04ca1aac45487793a2d50b20297d29b and 1d0b623672f5acaea868dc5d76e111187d6d5767)
  • These can be changed through the dynamic settings in Django admin

Improvements

• Made it possible to search for all member fields in the member list - not just the ones visible in the list (37aa4201d40910df787061271d9c7fed418fedf5)
• Improved translation of the quit/retired error messages (8769f9ce3237fc697396b82f50d58639ce1b02e9)

Fixes

• Fixed missing card numbers being displayed as "None" instead of simply showing a blank field, in the member list (80942a2290588dd517f9b1e44bf11c567f23f1bf)

Other changes

• Moved constance first in the Django admin app list (d9ecf6a2d3186798f67b59419639486022ff15e8)

Areas to review closely

Check that the search bar on the member list page does indeed search for all (interesting) fields.

Deployment notes

Should set proper values for the ENROLL_MEMBERS_GUIDE_LINK, RETIRE_MEMBERS_GUIDE_LINK and QUIT_MEMBERS_GUIDE_LINK settings (through https://admin.makentnu.no/constance/config/ - after these changes have been deployed).

Checklist

(If any of the points are not relevant, mark them as checked)

• [x] Created tests that fail without the changes, if relevant/possible
• [x] Made sure that your code conforms to the code style guides and that any common code smells have been addressed
  • (It's not intended that you read through this whole document, but that you get yourself an overview over its contents, and that you keep it in mind while taking a second look at your code before opening a pull request)
• [x] Added sufficient documentation - e.g. as docstrings or in the README, if suitable
• [x] Added your changes to the "Unreleased" section of the changelog - mainly the changes that are of particular interest to users and/or developers, if any
• [x] Added a "Deployment notes" section above, if anything out of the ordinary should be done when deploying these changes to the server

[ddabble]

Merging without explicit approval from another member, as the Dev committee agreed to merge these changes and assume they're relatively bug-free, simply to get things done quicker.