Slice 6: Decouple IntegrationsBody from auth options utilities

[mnholtz]

Motivation See phase spec linked in the implementation sketch, but we'd like to reuse IntegrationsBody in the app for deployment configuration. We are currently unable to do this due to the coupling with auth options.

Implementation sketch https://www.notion.so/pixiebrix/Make-it-easy-to-find-and-configure-the-mod-you-want-to-deploy-fddb70aeb41142ed9bda27010f83c92e?pvs=4#70eca3919f5a4dfc95edd965e0dc21b6