BIOS back to Text Only by default

Greetings,

A while ago, I removed GZIP and BZIP2 support from the boot loader by
default to get it to fit into the space available for BIOS booting with the
lua interpreter for PXE booting.

This made it into the 13.4 Release. Some downstream distributions started
needing to build their own loader for this release. Their MFS setup relied
on either gzip or bzip2 files working and my changes broke that.

After talking with people at places like EuroBSDcon, irc and Discord, I
think I'll take Mark Johnson's idea of moving back to a Text-only boot
loader for BIOS by default, and putting these two options back into the
loader.  When we do this, the loader shrinks 20k net (-40k for graphical
loader, +20k for decompression).

My thoughts are that you can boot either with the graphical or text-only
loader. There's no real functional difference, apart from aesthetics. While
they are nice to have, when space is tight, we should bias towards keeping
functional things over keeping things that are just pretty when we need to
make a choice.

EFI booting remains unchanged.

I'd like to get this in over the next week or so. I'm soliciting comments
on this idea. I've created https://reviews.freebsd.org/D47203 for this
change. I've not regenerated the options docs yet, but I'll do that as well.

Comments?

Warner