MFC r259113, r259115, r259144, r259148:

r259113 (dteske):
Fix failed attempt to send pkg(8) stderr to /dev/null

r259115 (dteske):
Prevent truncating /tmp/bsdinstall_log each time we
exec a module.

r259144 (dteske):
Fix a regression after successfully installing to encrypted
ZFS root, the passphrase is not accepted and a message about
"incorrect key" is displayed.

r259148 (dteske):
Fix a regression resulting in mountroot prompt after attempting
to install to encrypted ZFS root (caused by a typo in a
variable name -- ZFSBOOT_BOOT_FSNAME -> ZFSBOOT_BOOTFS_NAME).

Sponsored by: The FreeBSD Foundation

MFC Revisions:
256549: man-page updates
256551: .Dd bump in manpage
256553: bootenv -> ROOT fix
257842: monster list of fixes
257843: minor touchup
257844: copy install log
257845: fixup to last
257872: mdoc fixup
257939: debug check
258021: MBR bootcode fixup

Reviewed by: many
Discussed on: -current
Approved by: re (hrs)

MFC revisions 256321-256323,256331,256333,256335,256343:
Bring in a new zfsboot auto script for performing automatic setup of a boot
pool (optionally encrypted) with many other options, validations, features.
Originally submitted by Allan Jude; modified in collaboration.

MFC revisions 256325,256330,256345:
Rewrite the keymap selection menu to display keymaps and provide a test
mechanism. Test mechanism originally submitted by Warren Block; modified.

MFC r256347:
Prominently display "Wireless" for each wireless network interface. Part
of PR bin/161547; submitted by Warren Block; slightly modified.

MFC r256348:
Remove the dumpdev configuration dialog, merge it into the regular
services configuration and enable it by default. Originally submitted by
Allan Jude; slightly modified.

PR: bin/161547
Submitted by: Allan Jude, Warren Block <wblock@wonkity.com>
In collaboration with: Allan Jude <freebsd@allanjude.com>
Approved by: re (glebius)

MFC r259113, r259115, r259144, r259148:

r259113 (dteske):
Fix failed attempt to send pkg(8) stderr to /dev/null

r259115 (dteske):
Prevent truncating /tmp/bsdinstall_log each time we
exec a module.

r259144 (dteske):
Fix a regression after successfully installing to encrypted
ZFS root, the passphrase is not accepted and a message about
"incorrect key" is displayed.

r259148 (dteske):
Fix a regression resulting in mountroot prompt after attempting
to install to encrypted ZFS root (caused by a typo in a
variable name -- ZFSBOOT_BOOT_FSNAME -> ZFSBOOT_BOOTFS_NAME).

Sponsored by: The FreeBSD Foundation

MFC Revisions:
256549: man-page updates
256551: .Dd bump in manpage
256553: bootenv -> ROOT fix
257842: monster list of fixes
257843: minor touchup
257844: copy install log
257845: fixup to last
257872: mdoc fixup
257939: debug check
258021: MBR bootcode fixup

Reviewed by: many
Discussed on: -current
Approved by: re (hrs)

MFC revisions 256321-256323,256331,256333,256335,256343:
Bring in a new zfsboot auto script for performing automatic setup of a boot
pool (optionally encrypted) with many other options, validations, features.
Originally submitted by Allan Jude; modified in collaboration.

MFC revisions 256325,256330,256345:
Rewrite the keymap selection menu to display keymaps and provide a test
mechanism. Test mechanism originally submitted by Warren Block; modified.

MFC r256347:
Prominently display "Wireless" for each wireless network interface. Part
of PR bin/161547; submitted by Warren Block; slightly modified.

MFC r256348:
Remove the dumpdev configuration dialog, merge it into the regular
services configuration and enable it by default. Originally submitted by
Allan Jude; slightly modified.

PR: bin/161547
Submitted by: Allan Jude, Warren Block <wblock@wonkity.com>
In collaboration with: Allan Jude <freebsd@allanjude.com>
Approved by: re (glebius)