loader: Change this BIOS tradeoff: Add back zip and use text only

After talking with a number of people about the removal of some things
to make the loader fit, readjust things a little.

Add back GZIP and BZIP2 compression support. Many of the downstream MFC
packaging systems depend on this. This adds back 20k to the size of the
loader.

Make the boot loader text-only by default. This saves 40k in size. Net,
we're 20k smaller. The graphics loader for BIOS is less useful than the
zip functionality: You can still boot w/a text only one it and you can
build a custom one if you really want it. It's also the default we use
for dual console.

This should be merged back into stable/14 and stable/13 so it's in the
next release for each of these. That way we have only one release (13.4)
with the other defaults.

MFC After: 3 days
Sponsored by: Netflix
Reviewed by: olce, rgrimes, emaste
Differential Revision: https://reviews.freebsd.org/D47203

(cherry picked from commit 23dee252daf2ff60e521c9c019e64134b63ce90f)