Support IAM Authentication for AWS DocumentDB (MongoDB Compatible) by Skipping Password Validation

[loknirvan]

AWS RDS DocumentDB (MongoDB-compatible) has introduced IAM authentication, requiring the creation of users in the $external database. According to the specifications, DocumentDB throws an error if a password is provided for IAM users, as they do not require a password. However, in the current Terraform provider, the password field is mandatory, causing a validation error before applying changes. This story involves updating the provider to handle IAM users without requiring a password, ensuring smooth integration with the new authentication method.

Acceptance Criteria:

1. Modify the provider to allow the creation of users in the $external database without a password when using IAM authentication.
2. Ensure no validation errors occur when a password is not provided for IAM users.
3. Validate the successful creation of IAM-authenticated users in AWS DocumentDB without password requirements.

AWS IAM Authentication with DocumentDB (Mongodb compatible) documentation