Add support for STS-issued AWS credentials

[tariqajyusuf]

Is your feature request related to a specific problem?

When using either the CLI or the Fides web interface, the AWS resource scanner requests an access key ID and secret. This means that users can only use long-term credentials which goes against AWS best practices. Best practices indicate to use temporary security credentials

Describe the solution you'd like

Adding an additional CLI argument (e.g. --session_token) that allows for just-in-time creation and use of temporary keys created by STS.

Describe alternatives you've considered, if any

Alternative would be provisioning a long-term access key.

Additional context