implementing DOWNLOAD_EXTRA_CONFIGS

[Crafter-Y]

Related to: #3658

This PR aims to provide a way to download configs or other files before server startup in order to patch them.

With this change, files can be downloaded by using the DOWNLOAD_EXTRA_CONFIGS environment variable.

For example:

DOWNLOAD_EXTRA_CONFIGS: "plugins/test<https://raw.githubusercontent.com/itzg/docker-minecraft-server/refs/heads/master/.editorconfig,plugins/WorldEdit<https://raw.githubusercontent.com/itzg/docker-minecraft-server/refs/heads/master/Dockerfile"

or

DOWNLOAD_EXTRA_CONFIGS: |
  plugins/test<https://raw.githubusercontent.com/itzg/docker-minecraft-server/refs/heads/master/.editorconfig
  plugins/WorldEdit<https://raw.githubusercontent.com/itzg/docker-minecraft-server/refs/heads/master/Dockerfile

The backend mc-image-helper function mcopy was enhanced by itzg/mc-image-helper#641

There is currently no option to provide file listings like with MODRINTH_PROJECTS since mcopy needs an extra flag for that.

I also did not try to integrate the existing downloading of config files into this, because I feel like it should stay seperate.

I haven't documented the change yet, because I don't know where to put it best. Maybe the /configuration/misc-options/ ?

[itzg]

I haven't documented the change yet, because I don't know where to put it best. Maybe the /configuration/misc-options/ ?

I see what you mean that there's not a perfect spot for it. I think I prefer the one you found. Another that might be ok is the top level https://docker-minecraft-server.readthedocs.io/en/latest/mods-and-plugins/ since it mentions /config mount.

[itzg]

Code changes look good

[Crafter-Y]

I don't know why CI fails. Docs are good like that?

[itzg]

I don't know why CI fails. Docs are good like that?

I'll re-run. I think it was just waiting for my approval.

[itzg]

Docs look great. I'll see what the build thinks 😉