add container env 'DLC_SPACE_AGE' support

[Kariton]

fixes #51

rebase / version bump follows when #50 is merged.

[Kariton]

was unsure what you would prefer - the "technical" term or the "human" version.
e.g.: DLC_SPACE_AGE / enable_space_age

also updated the comments to match those from the container repo.

[Fank]

I went for DLC_SPACE_AGE because the environment scope is quite limited for naming, and since its a DLC i went for DLC prefix.
But here i would recommend using enable as prefix, its easier to understand.

[SQLJames]

pending merger for #50 Because we will need to bump the chart version to 2.0.1 here.

[Kariton]

lol.

this time my own run failed the first time.
second time worked...

https://github.com/Kariton/factorio-server-charts/actions/runs/11477874206/job/31941033773

[Kariton]

something odd is happening with the GH workflow

[Kariton]

your chart release GH token seems to be expired. ;)

[SQLJames]

its fixed now and merged in, still getting weird instances of that rcon port but ill dig into that likely this weekend and maybe add more tests as well.