Designate a particular enabled source as the default one, and make /admin/modules/browse redirect to it

This should be backported to 2.0.x.

Still assigned to myself for tests.

We need to figure out an approach for indicating to the user which source they're on if they're on the "/browse" route alone. Either work it through the menu system, or just redirect from the main route to the default sub-route. Either is acceptable to me.

Implemented a redirect for that - super easy! Barely an inconvenience!

This will get some cleanup later, when there are bigger and better plans for the "Extend" section altogether. This is good for now.

I think it's weird and bad to effectively re-execute the same controller. But as I said above, we can clean up later -Tim P.

chrisfromredfin → credited tim.plunkett → .

in on 2.1.x and clean cherry-pick to 2.0.x

done!