Migration of users and accounts

Manager users will not be able to read or write to containers (unlike in Vault Mode). These users have to be provisioned via the service API on the Accessers (storage accounts and credentials). Only AWS style authentication is supported in Container Mode. The credentials created via service API will have to be used by the users to make IO requests.

During Vault Mode conversion, the Manager account and credentials associated with standard vaults are migrated to the storage account and credentials on Accesser devices.