Make member modal change URL + moved JS code to `<head>` and/or separate files

Proposed changes

Made opening/closing the member modal in the member list change the browser URL (84dab5708ffcb9884de3e6b889d6c5f6812c57b6, f5e30d0d966f1826e36fa502a73a184391857c6b, 0b1942f3f98eaefc94a3be473b8abd7df8699bad, e8fa87862b121127375541cd2b594b6e9e3e79a7)
- This makes it possible to navigate backwards and forwards using e.g. the back/forward buttons on a mouse, or the back button on most Android devices. It also makes it easier to get the URL for linking directly to a specific member's info in the member list.

Moved JavaScript code to the <head> tag (through the extra_head block) and/or separate files (9837396a9667c2a73a391d7567b769afd72ceee0)
- See the commit message for further details
- Also removed the extra_scripts block from all templates, as it isn't used anymore

Fixed always auto-scrolling to the first toggle button when opening a member's info modal in the member list (938fa8b2c3df5e8066ca571c0e8d4f8933eea06e)
- The modal should now instead open with the previous scroll position when hiding and re-showing it (even when showing a different member)

Renamed the member_list path with a pk parameter, to member_detail (98f215f3a46da1a88928028142968684c31d8968)

That the member modal navigation works properly, and that all the moved JavaScript code still works as intended.

(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