Adds a given binary file to AWS Secrets Manager as base64 - this is only possible via the CLI or SDK as it's not supported in the AWS Console UI at this time
First argument is used as secret name - if not given prompts for it
Second argument must be a binary file such as a QR Code screenshot - this is converted to base 64 because AWS only permits ASCII characters in this value
Third or more args are passed to 'aws secretsmanager'