Add V2 API routes to download an envelope's certificate and audit log
separately, and align the internal cert/audit log downloads to use
envelopeId.
Enforces document visibility via getEnvelopeWhereInput and loads field
signatures so certificates render correctly.
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.
Lucas Smith
David Nguyen