reflog exists: use parse_options() API
Change the "reflog exists" command added in
afcb2e7a3b8 (git-reflog:
add exists command, 2015-07-21) to use parse_options() instead of its
own custom command-line parser. This continues work started in
33d7bdd6459 (builtin/reflog.c: use parse-options api for expire,
delete subcommands, 2022-01-06).
As a result we'll understand the --end-of-options synonym for "--", so
let's test for that.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>