CI: Test toolchain and bundle images against OHOS codebase

Fetch OpenHarmony OS codebase release tarballs and test
oniro-openharmony-toolchain and oniro-openharmony-bundle against these.

In order to save CI resources, only MR pipelines run these new jobs
automatically.  For normal branch pipelines, the job are set to manual, so
developer can choose to run them as needed.

Signed-off-by: Esben Haabendal <esben.haabendal@huawei.com>