Create image_tag_mutability variable to allow user to specify whether the ecr repository should be mutable or immutable

[jross-ai]

Describe the Feature

Allow users to specify whether the ecr repository image tag should be mutable or immutable

Expected Behavior

Pass in a variable such as ecr_image_tag_mutability that will then get passed to the ecr module and be used to specify the image_tag_mutability

Use Case

By default the image_tag_mutability variable on the ecr module is set to IMMUTABLE. I would like to set this variable to MUTABLE.

Describe Ideal Solution

A variable such as ecr_image_tag_mutability is added and is passed as the image_tag_mutability variable in the ecr module.

Alternatives Considered

I could fork this repository and implement this fix myself, but I would like to continue to benefit from the updates that are provided by the team at cloudposse.

Additional Context

Really appreciate all of the work the cloudposse team is doing!