chore: Switch ECS module sources back to main project and off the forked copy; pin Aurora version

[bryantbiggs]

Description

• Now that feat!: Add support for creating ECS service and container definition terraform-aws-modules/terraform-aws-ecs#76 is merged, the module source is switched back to the main project and off of the fork
• Add a loose version pin to the Aurora module; there was a recent major change that removed the random password generation for the now preferred Aurora managed master password via SecretsManager and simplification of security group rules

Motivation and Context

• Remove use of forked copy of modules and pin to avoid any surprises
• Closes change service definition cluster keyword to cluster_arn #132

How Has This Been Tested?

• I have tested and validated these changes using one or more of the provided examples/* projects
• I have executed pre-commit run -a on my pull request

[mbeacom]