Provide an arm64 image for Karura #2090
Description
Following-up on this issue: open-web3-stack/parachain-launch#70
It would be nice to demo parachain-launch in hackathons and have it work out-of-the-box with the default config for linux and mac users. Since there is an ever-growing population of mac users (especially in hackathons), the request is for Acala to provide an arm64 Docker image for Karura.