WIP Add support for DSQL iam authentication

[leszek-bq]

Summary

Add support for DSQL iam authentication

Description

• Created TokenUtils base class and specific implementation of token generation code for DSQL
• Moved the token generation code from the /utils/iam_auth_utils.ts to specific TokenUtils implementation
• Added a parameter to IamAuthenticationPlugin constructor for the new TokenUtils and updated the corresponding IamAuthenticationPluginFactory
  • Did the same for the FederatedAuthPlugin and the OktaAuthPlugin and their factories
  • Created a new DsqlIamAuthenticationPluginFactory
• Added example examples/aws_driver_example/dsql_aws_iam_authentication_postgresql_example.ts

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[leszek-bq]

Note:
The first push is just code implementation and it is work in progress. The implementation works with the tests:

• examples/aws_driver_example/dsql_aws_iam_authentication_postgresql_example.ts
• examples/aws_driver_example/aws_iam_authentication_postgresql_example.ts

It is expected that some unit tests related to the IamAuthenticationPlugin, FederatedAuthPlugin and the OktaAuthPlugin are failing because of the changed interfaces.
The next step will be to fix the unit tests.