graphics/openboard: New port: Interactive whiteboard

OpenBoard is an open source cross-platform interactive whiteboard
application designed primarily for use in schools. It was originally
forked from Open-Sankore, which was itself based on Uniboard. It
supports digital pens, virtual keyboards, PDF import, web browsing,
video playback, and screen annotations.

WWW: https://www.openboard.org/
https://github.com/OpenBoard-org/OpenBoard/

Patches reported to upstream:
https://github.com/OpenBoard-org/OpenBoard/pull/1489
https://github.com/OpenBoard-org/OpenBoard/pull/1490

PR: 295104
Sponsored by: UNIS Labs