Fix restoring of Config Files

[glowredman]

Previously, if the ./config/modpack-update file was shipped with a pack, it wouldn't have been deleted. This would've triggered the restoreLocalConfig() method each time instead of only once after the update and backupLocalConfig() every following start. The code responsible for this was commented out. I uncommented it and tested it (using Technic Solder) and couldn't find any issues.

Allows GTNewHorizons/GT-New-Horizons-Modpack#13971 to work.

Other improvements:

• Made command responses translatable
• Replaced java.io.File#delete() with java.nio.Files#delete(java.nio.Path) in a try-catch-block to be able to log the reason should the deletion fail.
• Fixed /defaultconfigs createUpdateFile command
• Updated buildscript