bectl: log modifying functions to zpool history

Modeled directly after the method used by the zfs/zpool commands: flag
commands with a "please log me" flag, and when there, reconstruct the
command line. On success, call the library function to add it to the
log.

(Majority of the change by Rob; minor edits by kevans@)

Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Co-authored-by: Kyle Evans <kevans@FreeBSD.org>
Sponsored by: Modirum MDPay
Sponsored by: Klara, Inc.