Add new workshop tag for translation mods

[JavidPack]

Fixes #3855 . Adds a new tag for mods with translationMod = true in build.txt. The build.txt wiki page further explains the translationMod option.

This PR also fixes an exception while publishing a mod for the first time that puts the menu in a weird state. Not sure if the fix is correct, or if WorkshopHelper.TryGetModDownloadItemsByInternalName needs to be reworked more.

TODO:

• Add the tag to steam
• Decide on tag name.
• Collect initial translations
• Decide if work should be done to prevent non-translationMods from setting the tag.