Add and document new environmental variables for using custom beta ve…

…rsions. (#443)

* Add support for custom beta flags.

* Document new environmental variables.

* Correct the environmental variable for beta password.

* Simplify beta definition.

* Cleanup

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Co-authored-by: Robert Thomas <[email protected]>

Bump `saveshare` dependencies

Automatically set external reliable messaging port (#418)

Update run.sh

Fix script permissions

Fix Steamcmd download error (#389) (#394)

Copy some Steam files to the newly created user's home directory.

Move upgrade info to the wiki

Overhaul rootless implementation (#364, #389, #393)

Typo

Revert to Ubuntu 22 (fixes #380, reverts #334)