chores: Easy to use bundled executable

[SomePersonFromMars]

One of the following methods would probably be the simplest:
https://libgdx.com/wiki/deployment/bundling-a-jre

[SomePersonFromMars]

Construo is used now for packaging. Downgrade to Java version 16 was necessary, because Construo relies on removed sun.reflect API.

A better solution would probably be to use jpackage, as it supports newer Java versions. Another option is to use GraalVM as it would provide an all-in-one executable that does not require a JRE bundled with the executable. Packr is not very useful as it bundles the executable along with the full JRE, which takes too much disk space.