### Is there an existing issue for this?

- [X] I have searched the existing issues

### Feature description

The use case I have in mind is to run Node 16.x Lambdas - the default container registry is `lambci/lambda` which is effectively abandoned. [Not even Node 14.x has been published](https://github.com/lambci/docker-lambda/pull/330). However, switching the registry over to [`amazon/aws-lambda-nodejs`](https://hub.docker.com/r/amazon/aws-lambda-nodejs) still fails to pull the container, since localstack is looking for the tag `nodejs16.x`. I'd like to be able to specify that if the runtime is `nodejs16.x` it just looks for tag `16`.

### 🧑‍💻 Implementation

_No response_

### Anything else?

_No response_
files_to_add: Dict[str, str]
    
    env_updates: Dict[str, str]
    
    updated_command: Optional[str]
    
    updated_handler: Optional[str]
    def __init__(
        self,
        files_to_add=None,
        env_updates=None,
        updated_command=None,
        updated_handler=None,
    ):
        self.files_to_add = files_to_add or {}
        self.env_updates = env_updates or {}
        self.updated_command = updated_command
        self.updated_handler = updated_handler
class InvocationResult: