MFC: r293001
Introduce the ZFS Boot Environments menu to the loader menu

MFC: r293414
Add ZFS Boot Environments menu to userboot

MFC: r293454
Only call init_zfs_bootenv when the system is booted with ZFS

MFC: r293612
Fix calling init_zfs_bootenv to early, resulting in empty ZFS BE menu

Relnotes: yes
Sponsored by: ScaleEngine Inc.

MFC r286368: Remove guards around overwriting loader.rc and menu.rc

There have been .local version of each for user modifications for some time
This allows users to receive future updates to these files

PR: 183765
Differential Revision: https://reviews.freebsd.org/D3176
Submitted by: Bertram Scharpf, Nikolai Lifanov (patch)
Reviewed by: dteske, loos, eadler
Approved by: bapt (mentor)
Relnotes: yes
Sponsored by: ScaleEngine Inc.

MFC revisions 277693,278335,280382-280385,280923-280926,280931,
280933-280939,280974-280976,281002,281009,281081,281176-281180,
281271,281275,281616 (described in-breif below):
r277693: Font fix (des)
r278335: Revert that
r280382: Whitespace, comments, and copyright update
r280383: Prevent inadvertent bootlock condition
r280384: Increase max passowrd length from 16 to 255 chars
r280385: Add missing variable hints to loader.conf(5) defaults
r280923: Whitespace
r280924: Comments
r280925: Optimize bootmsg to use fg/bg/me from screen.4th
r280926: Whitespace and cleanup
r280931: Comments
r280933: Move beastie to logo-*.4th; brands to brand-*.4th
r280934: Add remainder of supported ANSI escape sequences
r280935: Securely overwrite (zero) user input after password checks
r280936: Use equals for ASCII double frames
r280937: Solve dreaded "dictionary full" issue
r280938: Add "GELI Passphrase:" prompt to boot loader
r280939: Revert that (premature commit)
r280974: Use fg/b/me from screen.4th instead of literals
r280975: Eliminate literal escape sequences from *.4th
r280976: Use ^[[m mode-ending versus ^[[37m
r281002: Install newly added brand-*.4th and logo-*.4th files (jkim)
r281009: Revert .PATH changes to fix mips build (jkim)
r281081: Make sure forth manpages are only installed once (bapt)
r281176: Back to previous mode-endings based on feedback
r281177: Back to previous mode-endings based on feedback
r281178: Back to previous mode-endings based on feedback
r281179: Back to previous mode-endings based on feedback
r281180: Eliminate literal escape sequences from *.rc
r281271: Fix a bootlock condition if loader_version is set
NB: Commit message of r281271 has a typo, s/_logo/_version/
r281275: Re-do proper mode-endings
r281616: Add "GELI Passphrase:" prompt to boot loader

Relnotes: Added "GELI Passphrase:" prompt to boot loader

MFC r258270:

Add a try-include word (which acts the same as "include") and use it to
conditionally include (but ignore failures) /boot/loader.rc.local and
/boot/menu.rc.local -- to make customizing the menu easier.

Reviewed by: alfred
Discussed on: -hackers

MFC r257650:

Defer loading of kernel and modules if the beastie menu is enabled. Add a
kernel selection menu to the beastie menu. List of kernels is taken from
`kernels' in loader.conf(5) as a space (or comma) separated list of names
to display (up to 9). If not set, default value is "kernel kernel.old".
Does not validate that kernels exist because the next enhancement will be
to allow selection of the root device.

Discussed on: -current

MFC revisions 277693,278335,280382-280385,280923-280926,280931,
280933-280939,280974-280976,281002,281009,281081,281176-281180,
281271,281275,281616 (described in-breif below):
r277693: Font fix (des)
r278335: Revert that
r280382: Whitespace, comments, and copyright update
r280383: Prevent inadvertent bootlock condition
r280384: Increase max passowrd length from 16 to 255 chars
r280385: Add missing variable hints to loader.conf(5) defaults
r280923: Whitespace
r280924: Comments
r280925: Optimize bootmsg to use fg/bg/me from screen.4th
r280926: Whitespace and cleanup
r280931: Comments
r280933: Move beastie to logo-*.4th; brands to brand-*.4th
r280934: Add remainder of supported ANSI escape sequences
r280935: Securely overwrite (zero) user input after password checks
r280936: Use equals for ASCII double frames
r280937: Solve dreaded "dictionary full" issue
r280938: Add "GELI Passphrase:" prompt to boot loader
r280939: Revert that (premature commit)
r280974: Use fg/b/me from screen.4th instead of literals
r280975: Eliminate literal escape sequences from *.4th
r280976: Use ^[[m mode-ending versus ^[[37m
r281002: Install newly added brand-*.4th and logo-*.4th files (jkim)
r281009: Revert .PATH changes to fix mips build (jkim)
r281081: Make sure forth manpages are only installed once (bapt)
r281176: Back to previous mode-endings based on feedback
r281177: Back to previous mode-endings based on feedback
r281178: Back to previous mode-endings based on feedback
r281179: Back to previous mode-endings based on feedback
r281180: Eliminate literal escape sequences from *.rc
r281271: Fix a bootlock condition if loader_version is set
NB: Commit message of r281271 has a typo, s/_logo/_version/
r281275: Re-do proper mode-endings
r281616: Add "GELI Passphrase:" prompt to boot loader

Relnotes: Added "GELI Passphrase:" prompt to boot loader

MFC r258270:

Add a try-include word (which acts the same as "include") and use it to
conditionally include (but ignore failures) /boot/loader.rc.local and
/boot/menu.rc.local -- to make customizing the menu easier.

Reviewed by: alfred
Discussed on: -hackers

MFC r257650:

Defer loading of kernel and modules if the beastie menu is enabled. Add a
kernel selection menu to the beastie menu. List of kernels is taken from
`kernels' in loader.conf(5) as a space (or comma) separated list of names
to display (up to 9). If not set, default value is "kernel kernel.old".
Does not validate that kernels exist because the next enhancement will be
to allow selection of the root device.

Discussed on: -current