Ability to configure the debug init container

Currently, [container images for debugging](https://skaffold.dev/docs/workflows/debug/#configuring-container-images-for-debugging) can only be configured to use [different registries](https://skaffold.dev/docs/design/global-config/). Having more configuration options to apply to the debug init container would be useful. For example, if Skaffold is deploying to a cluster that requires containers to specify `limits` or not to use the `latest` tag, these can be configured for the debug init container.