fix: include filtered containers in network inspect

[coderbirju]

Issue #, if available:
#384 did not pass the containers list to the response correctly, this PR fixes this issue and provides the correct response in the network inspect

Description of changes:

• adds GetContainers func that is a wrapper to the containerd.Containers function, accepts filters and returns a list of containers matching the filter criteria
• Calls getContainersFromNetConfig a new func that fetches the containers associated with the network name and appends that into the network inspect response.

Testing done:

• I've reviewed the guidance in CONTRIBUTING.md

License Acceptance

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.