Incorporate browser API sequence diagrams into the specification

[jogu]

As per https://github.com/openid/OpenID4VP/pull/155/files#r1653319017 there are some plantuml diagrams added in the browser API PR that are not incorporated into the specification.

We would like those diagrams to be incorporated into the specification.

To avoid synchronisation issues that should happen automatically when the specification is build (e.g. in the GitHub workflow: https://github.com/openid/OpenID4VP/blob/main/.github/workflows/Build-OID4VP.yml ).

It anyone is able to help us get that working it would be greatly appreciated.

[jogu]

Someone on today's WG call (sorry, I have forgotten who!) suggested this tool might be part of a solution:

https://pypi.org/project/pandoc-imagine/