add /tu/ (get) index

This commit implements the '/tu' Trusted User index page.

In addition to this functionality, this commit introduces
the following jinja2 filters:

- dt: util.timestamp_to_datetime
- as_timezone: util.as_timezone
- dedupe_qs: util.dedupe_qs
- urlencode: urllib.parse.quote_plus

There's also a new decorator that can be used to enforce
permissions: `account_type_required`. If a user does not
meet account type requirements, they are redirected to '/'.

```
@auth_required(True)
@account_type_required({"Trusted User"})
async def some_route(request: fastapi.Request):
    return Response("You are a Trusted User!")
```

Routes added:

- `GET /tu`: aurweb.routers.trusted_user.trusted_user

Signed-off-by: Kevin Morris <kevr@0cost.org>

templates/partials/archdev-navbar.html

@@ -7,11 +7,29 @@
         {% endif %}
         <li><a href="/packages/">{% trans %}Packages{% endtrans %}</a></li>
         {% if request.user.is_authenticated() %}
+
+            {% if request.user.is_trusted_user() or request.user.is_developer() %}
+                <li>
+                    <a href="/requests/">{% trans %}Requests{% endtrans %}</a>
+                </li>
+
+                <li>
+                    <a href="/accounts/">{% trans %}Accounts{% endtrans %}</a>
+                </li>
+            {% endif %}
+
             <li>
                 <a href="/account/{{ request.user.Username }}/edit">
                     {% trans %}My Account{% endtrans %}
                 </a>
             </li>
+
+            {% if request.user.is_trusted_user() %}
+                <li>
+                    <a href="/tu">{% trans %}Trusted User{% endtrans %}</a>
+                </li>
+            {% endif %}
+
             <li>
                 <a href="/logout/?next={{ next }}">
                     {% trans %}Logout{% endtrans %}