Flatpak

I have created a [Flatpak](https://flatpak.org) for Chunky. This makes it way easier for Linux User to install Chunky. If you publish it on [Flathub](https://flathub.org), it's just a single click. The Flatpak ships with Java and OpenJFX, so there is nothing the User need to do. Just install it and start it from the Menu.

[Here are the build files](https://github.com/chunky-dev/chunky/files/14050622/Chunky.zip). Currently it skips the Launcher, as it needs extra arguments to find OpenJFX, so it needs a little bit of work before publishing it. Tell me, if you are interested.