This updates ConfigureView to build most of the page state needed for

the configure page. This is less messy than doing it in the template,

more expandable, and allows us to reuse some state computation that

already existed on the Python side.
In the process, we get to remove the staticfiles template tag, which

doesn't exist on Django 3.2, and a bunch of tabs-vs-spaces issues have

been cleaned up.

Successfully configured Review Bot, changing broker URL settings and

seeing new broker status information. Also verified that the user shown

for Review Bot had all the correct information.