Feature request: Connect Docker instance to multiple networks

### Describe your idea/feature/enhancement

In some complex scenarios (eg. using localstack with some other dependency) it may be useful to connect the Lambda with multiple Docker Networks.

Docker already supports the functionality of connecting one container to multiple networks, so it would just be a matter of exposing a new option so that a list of networks can be provided.

### Proposal

Expose `--docker-networks` (or accept multiple `--docker-network` values).

### Additional Details