Support write-only parameters for setting the master user credentials

[komaspieler]

Is your request related to a new offering from AWS?

Yes, the master_password_wo argument is available in the current provider: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/rds_cluster#master_password_wo-1

Is your request related to a problem? Please describe.

Currently, the module stores the master_password parameter plaintext in the terraform state which is not ideal.

Describe the solution you'd like.

It should be possible to decide whether ephemeral credentials should be used to create the database instance or whether it is okay to store the credentials in the state.

Describe alternatives you've considered.

I'm not aware of any other methods that could be used to avoid storing the master_password value in the state besides allowing AWS to manage the credentials, which is often undesirable.

Additional context

[komaspieler]

Already covered by #513

[github-actions]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues. If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.