Admin page accessible from internal pages

[TheStrgamer]

Proposed changes

Made the administration page accessible from the dropdown menu in internal pages, so you don't have to go back to public pages to access it.

Checklist

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

• Remembered to run the makemigrations, makemessages and compilemessages management commands and committed any changes that should be included in this PR
• Created tests that fail without the changes, if relevant/possible
• Manually tested that the website UI works as intended with different device layouts
  • (Most common is to test with typical screen sizes for mobile (320-425 px), tablet (768 px) and desktop (1024+ px), which can easily be done with your browser's dev tools)
• Manually tested that everything works as intended when logged in as different users locally
  • (This can be e.g. anonymous users (i.e. not being logged in), "normal" non-member users, members of different committees, and superusers)
• Made sure that your code conforms to the code style guides
  • (It's not intended that you read through this whole document, but that you get yourself an overview over its contents, and that you use it as a reference guide / checklist while taking a second look at your code before opening a pull request)
• Attempted to minimize the number of common code smells
  • (See the comment for the previous checkbox)
• Added sufficient documentation - e.g. as comments, docstrings or in the README, if suitable
• 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
• Added a "Deployment notes" section above, if anything out of the ordinary should be done when deploying these changes to the server
• Structured your commits reasonably
  • (Some tips on this can be found in "Write Better Commits, Build Better Projects" and in the code style guides)
  • (Restructuring commits after they've already been committed, can be done using e.g. interactive rebase; see the Git docs on rewriting history)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.17%. Comparing base (5715a77) to head (8ed38da).
Report is 1 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #755   +/-   ##
=======================================
  Coverage   88.17%   88.17%           
=======================================
  Files         152      152           
  Lines        6198     6198           
=======================================
  Hits         5465     5465           
  Misses        733      733           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[ddabble]

From a UX perspective, I don't think this button should be in this menu, as it can easily be confused to mean "Administration of the internal pages (i.e. the site I'm currently on)" - given that we've been able to successfully create a mental separation between the public and internal site with our users, of course. And as it is now, it's just one extra click to get to the public pages, anyway :)

But if you all agree that the button should be there, I'd suggest wrapping it in the same check as is done on the public pages, so that unprivileged users are not met with a 403 page 🙂

Suggested change

	<a class="item" href="{% host_url 'admin_panel' host 'main' %}">
	<div class="text">{% translate "Administration" %}</div>
	</a>
	{% if user|can_view_admin_panel %}
	<a class="item" href="{% host_url 'admin_panel' host 'main' %}">
	<div class="text">{% translate "Administration" %}</div>
	</a>
	{% endif %}