decouple Pleroma frontends from Pleroma itself
This bug is for discussing the possibility of uncoupling Pleroma FE and Masto FE application bundles from Pleroma itself.
Part of the motivation is to allow people to run instances either headless, or with other frontends (such as Feather).
An issue to solve is making it easy to fetch and install a frontend bundle. Perhaps we can have that as part of the setup script.