Move GetAccountInformation() to a common location for AWS

[`GetAccountInformation()`](https://github.com/google/cloud-forensics-utils/blob/main/libcloudforensics/providers/aws/internal/ebs.py#L563) currently resides in the EBS lib but since leverages the `STS` service, it would be better suited in a common location since it may be used outside of EBS functions.