Migration from "bare-metal" install to docker-based

[aljaxus]

The most common issue with SkinSystem is that the system doesn't work because of some dependency issues, be it incorrect PHP setup, missing PHP modules, etc..

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From here on "bare-metal" means "hosted without any additional abstraction layers - eg. docker" and "directly on the host operating system" but not "directly on host hardware" as in the context of operating systems.

I'd like to suggest that we move from the "bare-metal" to Docker based installation first, meaning the the officially supported setup would be via Docker install.

Configuration options would be passed via environment variables - best (and most consistent way of doing this is by using docker-compose definition files, or via bash scripts ofc).

Improvements over current setup:

• Many server communities are now running their servers using Docker, a good example for docker-based game server panel is pterodactyl.
• Github provides their own container registry ( ghcr.io ). Container images can be build directly using CI (github actions) and pushed to the registry.
• Updating wouldn't be a hassle, just restart the container and you good.
• No issues with PHP dependencies and stuff as it'll be all "builtin" already

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The project would still support direct installs to a webserver, eg. shared web hosting.