Check if image already exists on ECR

[gutomaia]

First, congrats for the action. It really works, although, I have an use case that I'm strugling to make it go with.

My usual docker image has an base image that does not change as much. Then I really would like an skipIfTagExists or something like that.

Ex:
skipIfImageExists = v0.0.23

If that image tag already exists on ECR, there is no need to create the docker image or push anything. What do you think?

[modullar]

I'd rather want to remove the latest image that existed before pushing and tag the built updated built image with latest I still haven't figured out how to do this yet

[bryan-rhm]

I also would like to have this feature, on my use case we have tag immutability, so if the job is rerun and the image has been pushed it will fail