feat: Added UserAttributeUpdateSettings to Cognito

[lucashuy]

Issue #, if available:
#2496

Description of changes:
Added UserAttributeUpdateSettings to Cognito model.

Description of how you validated changes:
A sample template that contained the UserAttributeUpdateSettings property was run with bin/sam-translate.py before and after the changes to validate the property was picked up by the reference to the AWS::Cognito::UserPool in the function's events.

Checklist:

• Add/update unit tests using:
  • Correct values
  • Bad/wrong values (None, empty, wrong type, length, etc.)
  • Intrinsic Functions
• Add/update integration tests
• make pr passes
• Update documentation
• Verify transformed template deploys and application functions as expected
• Do these changes include any template validations?
  • Did the newly validated properties support intrinsics prior to adding the validations? (If unsure, please review Intrinsic Functions before proceeding).
    • Does the pull request ensure that intrinsics remain functional with the new validations?

Examples?

Please reach out in the comments, if you want to add an example. Examples will be
added to sam init through https://github.com/awslabs/aws-sam-cli-app-templates/

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