Update AWS SSO configuration handling (reading)

[ikeyan]

Support sso_session attributes and [sso-session] sections when reading from config in check and credential-process commands
https://docs.aws.amazon.com/cli/latest/userguide/sso-configure-profile-token.html

This PR does not update how configure profile and configure populate update the config.

[iainelder]

Addresses #84.

[dobesv]

Note that aws CLI no provides its own credential_process you can use:

https://awscli.amazonaws.com/v2/documentation/api/latest/reference/configure/export-credentials.html

For example:

credential_process = aws configure export-credentials --profile dev --format process

[iainelder]

@dobesv How does the the aws configure export-credentials command help here? Can you share more info in your example?

I don't actually use the sso-session style configuration yet, mainly because aws-sso-util doesn't generate it yet 😅

[dobesv]

How does the the aws configure export-credentials command help here?

I noticed that the aws-sso-util credential_process was not working with my profile, I think it doesn't support sso-session properly. The AWS CLI version does support it. If you're using the sso-session feature to setup your profile, you can use the AWS CLI credential_process to generate the credential for older AWS SDKs that don't support sso-session.