unified list command for all scripts

e.g. ./build boot roms list
./update blobs inject listboards
./build boot list
./build clean list

also this is now possible:
./build list
or maybe
./update list
^ would list directories in resources/scripts/build
and resources/scripts/update respectively

this script is added:
resources/scripts/build/command/options

call it like so, e.g.
./build command options resources/coreboot

this script is now used, for list functions in
other scripts.

Signed-off-by: Leah Rowe <leah@libreboot.org>

resources/scripts/build/command/options

@@ -0,0 +1,31 @@
+#!/usr/bin/env sh
+
+# Copyright (c) 2023 Leah Rowe <info@minifree.org>
+# SPDX-License-Identifier: MIT
+
+. "include/err.sh"
+
+items=1
+
+main()
+{
+	[ $# -gt 0 ] || \
+		err "No argument given"
+	listitems "${1}" || err "No items present under: ${1}"
+}
+
+listitems()
+{
+	[ -d "${1}" ] || \
+		err "Directory not does exist: ${1}"
+	for x in "${1}/"*; do
+		# -e used because this is for files *or* directories
+		[ -e "${x}" ] || continue
+		[ "${x##*/}" = "build.list" ] && continue
+		printf "%s\n" "${x##*/}"
+		items=0
+	done
+	return ${items}
+}
+
+main $@