Generate binary image using jlink

[mscottford]

By using jlink to create a custom JRE and embedding it into the executable, we won't need to ship the JRE in the production Docker image for freshli. And that should result in smaller builds.

Docs: https://badass-runtime-plugin.beryx.org/releases/latest/

• Add build task for generating custom runtime image with jlink
• Update README.md with instructions for running the new task
• Update acceptance test suite to run against the binary as built with jlink. (This is needed to confirm that we included the correct parts of the JRE. If we've missed anything then we should get runtime errors when those tests execute.)