graphics/epsonscan2: Add new port for Epson Scanners

This is a port of the Seiko/Epson Epsonscan2 scanner engine and GUI[1].

It provides a complete alternative to sane/xsane with its own scanner engine and GUI.
It also provides a sane back-end library (libsane-epsonscan2.so) so that it works with the sane package.

There are two parts to this port:

• graphics/epsonscan2 - the main scanner engine and GUI that works with (most) USB scanners
• graphics/epsonscan2-non-free-plugin - support for Epson's Linux binary that adds network access to scanners and usb access to some particular scanners

Please read the file %%PREFIX%%/lib/epsonscan2/Read_me.FreeBSD for notes on how to set this up and use it.

[1] https://download.ebz.epson.net/man/linux/epsonscan2_e.html

PR: 261891
Reviewed by: (partly) Tatsuki Makino <tatsuki_makino@hotmail.com>, diizzy@