Addons: allow users to opt-in into the beta addons

Show a small form to the user where they can enable/disable the new beta addons
on their project.

* Closes #212
* Requires readthedocs/readthedocs.org#10733

Author: humitos

readthedocsext/theme/templates/projects/addons_form.html

@@ -0,0 +1,30 @@
+{% extends "projects/project_edit_base.html" %}
+
+{% load i18n %}
+{% load crispy_forms_tags %}
+
+{% block title %}{{ project.name }} - {% trans "Addons" %}{% endblock %}
+
+{% block project_addons_active %}active{% endblock %}
+{% block project_edit_content_header %}{% trans "Addons" %}{% endblock %}
+
+{% block project_edit_sidebar_help_topics %}
+  {% include "includes/elements/link.html" with url="https://blog.readthedocs.com/addons-flyout-menu-beta/" text="Blog post: Addons flyout menu beta" is_external=True class="item" %}
+{% endblock project_edit_sidebar_help_topics %}
+
+{% block project_edit_content %}
+  <div class="ui info message">
+    {% blocktrans trimmed %}
+      Read the Docs addons are in beta. Give it a try now!
+    {% endblocktrans %}
+  </div>
+
+  <form class="ui form"
+      method="post"
+      action="{% url 'projects_addons' project_slug=project.slug %}">
+    {% csrf_token %}
+    {{ form|crispy }}
+
+    <input class="ui primary button" type="submit" value="{% trans "Save" %}">
+  </form>
+{% endblock %}

readthedocsext/theme/templates/projects/edit_base.html

@@ -17,6 +17,9 @@
         <a class="item {% block project_advanced_active %}{% endblock %}" href="{% url "projects_advanced" project.slug %}">
           {% trans "Advanced settings" %}
         </a>
+        <a class="item {% block project_addons_active %}{% endblock %}" href="{% url "projects_addons" project.slug %}">
+            {% trans "Addons" %} <i class="ui small grey fa-duotone fa-rocket"></i>
+        </a>
         <a class="item {% block project_domains_active %}{% endblock %}" href="{% url "projects_domains" project.slug %}">
           {% trans "Domains" %}
         </a>