Configuration order for apps with templates

[manthey]

It is common to let an app template override another app's template. The override order depends on the order the apps are installed. In would be good if application order had a more obvious way to determine which apps should come before others. For instance, if you want to override a template in drf_yasg, the local apps need to come before drf_yasg.

Currently, downstream packages need to sift through apps already listed in configuration.INSTALLED_APPS for ones with templates they want to override and insert their local apps before them. There should be a better way.