Validate and verify external cloud credentials for driver

An external cloud-specific object that the driver will use to login to the external cloud. The structure of this object varies per driver implementation. It is recommended to have dedicated credentials for logging in to the external cloud in order not to violate possible concurrent users policies of the external cloud. In case of the HERE Tracking loopback driver, the maximum allowed concurrent user account tokens is 3 per account, therefore it is recommended to create a separate HERE account and grant it the required privilege to update the connector's project, and use that account in externalCloudInfo.