Add support for css_classes in FormCheckBox

Had to go the `template` field route so the
css_classes value can be accessed in the template properly

python/nav/web/crispyforms.py

@@ -33,9 +33,10 @@ class FormCheckBox:
     :param field: A field to render as a checkbox field.
     """
 
-    def __init__(self, field):
+    def __init__(self, field, css_classes: Optional[str] = None):
         self.field = field
-        self.input_type = 'checkbox'
+        self.css_classes = css_classes
+        self.template = 'custom_crispy_templates/form_checkbox.html'
 
 
 class HelpField(Field):

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

@@ -6,8 +6,6 @@
   {% include 'custom_crispy_templates/submit_field.html' with input=field %}
 {% elif field.input_type == 'helpfield' %}
   {% include 'custom_crispy_templates/field_helptext_as_icon.html' with field=field.field %}
-{% elif field.input_type == 'checkbox' %}
-  {% include 'custom_crispy_templates/form_checkbox.html' with field=field.field %}
 {% else %}
   {% show_field field %}
 {% endif %}

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

@@ -1,11 +1,13 @@
-<div id="div_{{ field.auto_id }}" class="ctrlHolder{% if field.errors %} error{% endif %}{% if field.css_classes %} {{ field.css_classes }}{% endif %}">
-    <label for="{{ field.id_for_label }}">
-        {{ field.label}}{% if field.field.required %}<span class="asteriskField">*</span>{% endif %}
-        {{ field }}
-    </label>
-    {% for error in field.errors %}
-        <small id="error_{{ forloop.counter }}_{{ field.auto_id }}" class="errorField">
-            {{ error }}
-        </small>
-    {% endfor %}
-</div>
+{% with input=field.field %}
+    <div id="div_{{ input.auto_id }}" class="ctrlHolder{% if input.errors %} error{% endif %}{% if field.css_classes %} {{ field.css_classes }}{% endif %}">
+        <label for="{{ input.id_for_label }}">
+            {{ input.label}}{% if input.field.required %}<span class="asteriskField">*</span>{% endif %}
+            {{ input }}
+        </label>
+        {% for error in input.errors %}
+            <small id="error_{{ forloop.counter }}_{{ input.auto_id }}" class="errorField">
+                {{ error }}
+            </small>
+        {% endfor %}
+    </div>
+{% endwith %}