Pre-download plugin configs to allow patching on first startup

[Crafter-Y]

Hi, thanks for you great work!

I would be cool to have DOWNLOAD_EXTRA_CONFIGS from itzg/docker-minecraft-server working here as well.

I implemented it over there:

• Pre-downloading plugin configs to allow patching on first startup docker-minecraft-server#3658
• Implementing multiple destinations for mcopy donwloads mc-image-helper#641
• implementing DOWNLOAD_EXTRA_CONFIGS docker-minecraft-server#3679

[itzg]

Ah, yes, there's the same beginnings of it with DOWNLOAD_DEFAULTS.

You're welcome to implement it here too @Crafter-Y ;)

[itzg]

Actually...was easy enough to bring over, so almost done

[Crafter-Y]

wow, amazing!