CI: Test toolchain and bundle images against OHOS codebase

Closes eclipse/oniro-core/meta-openharmony#6 and eclipse/oniro-core/oniro#191 (closed)

.gitlab-ci/container/openharmony-builder/.gitconfig

+# SPDX-FileCopyrightText: 2021 Huawei Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+[user]
+	name = OSTC Builder
+	email = ostc-builder@example.org