Add standalone list_products and list_variants commands.

get_releases coming soon

Test: build/make/tools/envsetup/run_envsetup_tests
Bug: 340648588
Change-Id: I32e7b868d04656e39f277bb37661eadab9751d7c

bin/list_variants

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+# Copyright (C) 2024 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+echo user
+echo userdebug
+echo eng
+