sntl login should log into public.ecr.aws as well

[raylas]

Even though docker login public.ecr.aws is not required for public ECR image pulls, it can greatly reduce the likelihood of running into 400s as the result of lazy rate limiting on AWS's part.

Maybe add a --public flag?

[raylas]

For example:

aws ecr-public get-login-password --region us-east-1 | docker login --username AWS --password-stdin public.ecr.aws

Note: Specifying us-east-1 is a good idea.