git reflog [expire|delete]: make -h output consistent with SYNOPSIS

Make use of the guaranteed pretty alignment of "-h" output added in my 4631cfc20bd (parse-options: properly align continued usage output, 2021-09-21) and wrap and format the "git reflog [expire|delete] -h" usage output. Also add the missing "--single-worktree" option, as well as adding other things that were in the SYNOPSIS output, but not in the "-h" output. This was last touched in 33d7bdd6459 (builtin/reflog.c: use parse-options api for expire, delete subcommands, 2022-01-06), but in that commit the previous usage() output was faithfully reproduced. Let's follow-up on that and make this even easier to read. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>