1. Define the controller/manager interface for artifact and tag
2. Provide a null implementation for artifact manager
Signed-off-by: Wenkai Yin <yinw@vmware.com>
This commits does some basic init work for supporting OCI:
1. Create the artifact and tag model
2. Create database tables
Signed-off-by: Wenkai Yin <yinw@vmware.com>