mcopy needs an option to quietly ignore missing sources

[itzg]

The Paper defaults for new versions aren’t always present and this finishes with an error status

https://github.com/itzg/docker-minecraft-server/blob/a3ac903dfe349608c53e779c8ef083b5bf4be386/scripts/start-setupEnvVariables#L32

Reported in discussion

itzg/docker-minecraft-server#3533

[itzg]

[init] 2025-07-05 14:57:09+00:00 Downloading default configs, if needed
+ mc-image-helper mcopy --to /data/config --skip-existing --skip-up-to-date=false https://raw.githubusercontent.com/dayyeeet/minecraft-default-configs/main/1.21.7/paper-global.yml,https://raw.githubusercontent.com/dayyeeet/minecraft-default-configs/main/1.21.7/paper-world-defaults.yml
+ logWarning 'One or more default config files were not available from https://raw.githubusercontent.com/dayyeeet/minecraft-default-configs/main/1.21.7/paper-global.yml,https://raw.githubusercontent.com/dayyeeet/minecraft-default-configs/main/1.21.7/paper-world-defaults.yml'
++ getWarningColoredLogString 'One or more default config files were not available from https://raw.githubusercontent.com/dayyeeet/minecraft-default-configs/main/1.21.7/paper-global.yml,https://raw.githubusercontent.com/dayyeeet/minecraft-default-configs/main/1.21.7/paper-world-defaults.yml'