datasource: Refactoring datasources

To help alleviate naming collisions, move each of the datasources into their own package. In the near future, we are going to add support for new metadata services so make a distinction between the metadata service types. This will deprecate `--from-metadata-service` in favor of `--from-<type>-metadata=<address>`.
I don't think this warning is of any use, it will of course appear in upgraded systems and potentially worry users.