Mapping pack resources to target version

[nahkd123]

Pack indexes now have sourceGameVersion field, which you can define the version that the pack was originally made for. To use the pack on future versions, there are 2 ways:

• Just build the pack with targetGameVersion == sourceGameVersion and load it to client. It should work, but future game versions may choose to remove "fixers" for old version, just like what they have done in 1.19.3.
• Let Multipacks remap resources to new version. This can be defined in either multipacks.modifiers.json or Bundler (targetGameVersion argument).
  • User can choose to define in multipacks.modifiers.json if they are migrating from old game version to new game version. sourceGameVersion must be the same as what is defined in multipacks.modifiers.json.