Add support for blue/green updates

[acorncom]

Describe the Feature

AWS RDS has Blue/Green updates available for certain database engines (details at hashicorp/terraform-provider-aws#28042). As of hashicorp/terraform-provider-aws#28046, the aws_db_instance used in this module now supports blue_green_update as a flag.

Expected Behavior

We'd be able to use RDS Blue/Green updates out of the box

Use Case

I'm not yet at the point where we need this functionality, but I'm looking ahead at long-term needs for a client. Could be valuable to be able to do quicker updates

Describe Ideal Solution

I'd love to see this module start supporting this new feature. Might be able to do the work on this long-term, but was interested in whether there was an actual appetite to add it here or whether you think it'll get too complex to maintain.

Alternatives Considered

No response

Additional Context

No response