Add support for unsup

[caitlynrw]

Enhancement Type

New server type

Describe the enhancement

unsup (Una's Simple Updater) is an extension to the packwiz format which allows upgrading of the game components and supports pre-defined variants of a pack. It fills a similar niche to packwiz, but supports more exotic game configurations.

While this jar can be run as a java agent, it is unable to perform a 'cold start' given the Docker image needs a pre-existing sever jar.

The 'flagship' pack using unsup is Rewind Upsilon (a touchup of FTB Ultimate) and a reference usage can be seen in their server files (will download a .zip).