Use Official SDK Environment Variables

[osterman]

what

• Support AWS_DATA_PATH for the default path to the AWS configs (with perhaps the current fallback of HOME)
• Support AWS_CONFIG_FILE for the path to the standard config file
• Support AWS_SHARED_CREDENTIALS_FILE for the path to the credentials file

why

• Interoperability with other tools
• Embrace current conventions

references

• https://docs.aws.amazon.com/cli/latest/topic/config-vars.html
• https://boto3.amazonaws.com/v1/documentation/api/latest/guide/configuration.html

[russellballestrini]

@osterman PR welcome.