env/freebsd-amd64: add FreeBSD 13.0 image
env/freebsd-amd64: add FreeBSD 13.0 image

The loader in FreeBSD-13.0 now boots into graphical mode since
https://cgit.freebsd.org/src/commit/?id=b6d85a5f51e4147452b35d76478fb9e191b7734b.
Add a "blind" menu interaction mode to the expect script to enable
the dual video/serial consoles, so that the video mode switches
to text mode when the kernel boots (which is scriptable using SeaBIOS sercons).

Updates golang/go#45903

Change-Id: I3da18b7e016111d04878c963f37ffd66573b9404
Reviewed-on: https://go-review.googlesource.com/c/build/+/315277
Run-TryBot: Carlos Amedee <ab5e2bca84933118bbc9d48ffaccce3bac4eeb64@golang.org>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Carlos Amedee <ab5e2bca84933118bbc9d48ffaccce3bac4eeb64@golang.org>
Trust: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>

golang/build,golang/build,golang/build,golang/build