Add a template for handling fieldsets in a form.
Review Request #8374 — Created Sept. 1, 2016 and submitted
This splits out the logic for handling fieldsets into its own template (djblets_forms/admin/change_form_pae.html), allowing other templates to make use of it instead of having to reinvent their own logic.
Tested that existing pages (like the Settings pages) still work properly.
Used this in a form that needed to render fieldsets. Saw that forms both
with and without fieldsets worked correctly.