Apparently a PDF Document used to *be* a promise (a "thenable") but
that's not the case anymore. The loading promise has to be deref'd
explicitely. This is also the case for `page.render`, which is not a
thenable anymore.
Furthermore, the API seems to have changed to favor parameter
objects (getViewport) and setting callbacks (onPassword) rather than
having lots of positional parameters.
Finally, remove apparently long dead `disableWorker` feature in
`PDFSlidesViewer`, although really the entire thing should be
rewritten in modern javascript.
Part-of: odoo/odoo#100067
Xavier Morel
542cb1dc21