feat(notification): support multiple providers and mailing list synchronization#459

JoseSzycho wants to merge 2 commits intomaindatum-cloud/milo:mainfrom

2-update-contactgroupmembership-and-contactgroup-apis-to-support-multiple-providersdatum-cloud/milo:2-update-contactgroupmembership-and-contactgroup-apis-to-support-multiple-providersCopy head branch name to clipboard