arm64 build

[msgilligan]

It would be nice to have an ARM-64 build of the native image executable as well as arm64 docker containers (both the JIT and native-image versions)

[msgilligan]

See if we can use this HOW-TO to build AMD64 & ARM64: https://dev.to/cloudx/multi-arch-docker-images-the-easy-way-with-github-actions-4k54

See also: bmuschko/gradle-docker-plugin#967 (comment)

This commit 306de86 contains a build.gradle file that was able to build a multi arch version of the -jit version of the container image. This image was pushed to our Docker registry as version 0.3.8. (This is based upon bmuschko/gradle-docker-plugin#967 (comment)) (See also WIP PR #7)

[msgilligan]

OK PR #7 is updated to work properly on GitHub Actions (for the gradle.yml workflow, the graalvm.yml is not updated.)