Add class representing a Div

Just a blank div that can be customized with classes
and stuff.
replaces crispyforms Div.

python/nav/web/crispyforms.py

@@ -195,3 +195,18 @@ class and template definitions.
         form_id=form_id,
         form_class=form_class,
     )
+
+
+class FormDiv:
+    """A class representing a div in a form layout.
+
+    :param fields: A list of fields to include in the div.
+    :param css_classes: Additional CSS classes to apply to the div.
+    """
+
+    def __init__(
+        self, fields: Optional[list] = None, css_classes: Optional[str] = None
+    ):
+        self.fields = fields
+        self.css_classes = css_classes
+        self.template = 'custom_crispy_templates/form_div.html'

python/nav/web/templates/custom_crispy_templates/form_div.html

@@ -0,0 +1,11 @@
+{# NB! This form div can only render fields that are supported by custom_crispy_templates/_form_field.html #}
+
+<div
+  {% if field.css_classes %} class="{{ field.css_classes }}" {% endif %}
+>
+  {% block formdiv_content %}
+    {% for field in field.fields %}
+      {% include 'custom_crispy_templates/_form_field.html' %}
+    {% endfor %}
+  {% endblock %}
+</div>