Need to have a way to support sub-controllers for a controller

With AD-SAL it's possible to implement a network slicing use case by mean of the "container" concept. This bug is opened to track the decision about it's support for MDSAL as well.

The use-case level requirement is:

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We have a controller cluster, managing a physical network, medium large. The
administrator need to be able to "slice" the network by creating partitions of
it and on each of it assign different privilege access for different users and
applications.
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The proposal to achieve this mechanism is to create an equivalent way of achieving the "container" concept with MDSAL, essentially by allowing multiple services of the same type to be published with MDSAL and to have tagging of the services such that could be tracked based on their container.