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.
During our field rework that makes fields appear
more accurately between signing and the completed pdf we swapped to
using text fields. Unfortunately as part of that we dropped using the
Noto font for the text field causing ANSI encoding issues when
encountering certain characters.
This change restores the font and handles a nasty issue we had with our
form flattening reverting our selected font.
Previously we used the form flattening method from PDF-Lib
but unfortunately when it encountered orphaned form items
or other PDF oddities it would throw an error.
Because of this certain documents would fail to seal and
be stuck in a pending state with no recourse available.
This change rewrites the form flattening handler to be
more lenient when coming across the unknown opting to skip
items it can't handle rather than abort.
