It seems this is very valid requirement coming from API manager users. At this moment we do not have deployable API artifacts. When it comes to API management related artifacts its bit different from .war or .car archives. Because when we migrate API platform from one to another we need to migrate APIs, Applications, tokens, usage data and etc. And its not simple as we deploy war in another deployment. For the moment you can use following work around.
01. Create setup for QA environment.
02. Move API Manager database to production system after QA process completes.
03. Move User management related database or LDAP to production system after QA process completes,
04. Move registry database to production system after QA process completes.
05. Move repository/deployment/server folder to production system after QA process completes (run time artifacts migration) . If you have tenants in your system you might need to move tenant specific data as well. For that move
06. In addition to that if you are using BAM then move usage data as well(but recommend to use fresh usage data store for production as you don't need to mix up production and QA statistics).
Is seems bit complicate at the start but actually its very easy and reliable way of migrating between environments(actually it need database dump and restore + copy run time artifacts to new deployment). You can easily puppetize this or can have your own deployment tool.