Add a way to globally control where a form field name is placed relative to its input

[hmpf]

We want to be able to do "{{ form }} or "{{ form.as_div }}" in our templates. as_div in particular uses the template "django/forms/div.html".

We can override any default django form specific template via argus.htmx if we add "django.forms" to argus.htmx.appconfig._app_settings (after "argus.htmx"), and set FORM_RENDERER = 'django.forms.renderers.TemplatesSetting' in the same place.

Just for as_div the easiest/most robustly way is probably with a form mixin with either our own "as_div", or reuse "as_div" and use our own template by setting "template_name_div" on the form.

Discovered during #1110