Remove $FreeBSD$: one-line forth tag

Remove /^\\[\s*]*\$FreeBSD\$.*$\n/

loader: implement framebuffer console

Draw console on efi.
Add vbe framebuffer for BIOS loader (vbe off, vbe on, vbe list,
vbe set xxx).
autoload font (/boot/fonts) based on resolution and font size.
Add command loadfont (set font by file) and
variable screen.font (set font by size). Pass loaded font to kernel.

Export variables:
screen.height
screen.width
screen.depth

Add gfx primitives to draw the screen and put png image on the screen.
Rework menu draw to iterate list of consoles to enamble device specific
output.

Probably something else I forgot...

Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D27420

loader: use teken teminal emulator for x86 and uefi

Replace mini cons25 emulator with teken, this does enable us proper console
terminal for loader and will make it possible to implement different
back end callbacks to draw to screen.

At this time we still only "draw" in text mode.

Move sys/boot to stand. Fix all references to new location

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