Create Lucee 6.x images

[cybersonic]

At the moment we are only doing snapshots it seems rather than major version of the 6.x images.

This ticket is to track the building of 6.x images

[justincarter]

The current work in progress branch for Lucee 6.x support is here: https://github.com/lucee/lucee-dockerfiles/commits/wip-next/

I think the things left to address are:

• adding default JSON config files
• supporting XML file upgrades without the default/existing JSON file blocking the migration of the XML config (I think this is an issue for anyone expecting their existing XML files to just work?)
• single mode for 6.x by default (users can change back to multi-mode in their config files if they require it, though I would guess ~95% users would not)
• check which Java versions are/should be supported

[tomchiverton]

There's a ton of discussion on the finer points here : https://dev.lucee.org/t/lucee-6-0-no-docker-image-yet/13517/12