This PR is handles the changes required to support envelopes. The new
envelope editor/signing page will be hidden during release.
The core changes here is to migrate the documents and templates model to
a centralized envelopes model.
Even though Documents and Templates are removed, from the user
perspective they will still exist as we remap envelopes to documents and
templates.
Adds password reauthentication to our existing reauth providers,
additionally swaps from an exclusive provider to an inclusive type where
multiple methods can be selected to offer a this or that experience.
