JSON patches for MultiMC instances

This allows changing the Minecraft version in the instance without re-editing the component, and easier interoperability with other MultiMC features. More information about JSON patches can be found on the MultiMC wiki page about them. Here is a MultiMC instance demonstrating this.

Instructions:

Create a new MultiMC instance.
Click "Edit Instance".
Click "Add Empty". Enter "LaunchWrapper" for the name, and "org.mcphackers.launchwrapper" for the UUID.
Select the new component labeled "LaunchWrapper", and click "Edit".
Replace the contents of the file with something like this:

{
   "+traits": [
       "noapplet"
   ],
   "assetIndex": {
       "id": "empty",
       "sha1": "62ea787c1f800c091b98678b050453a5ae59d7bc",
       "size": 14,
       "totalSize": 0,
       "url": "https://mcphackers.github.io/assets/empty.json"
   },
   "libraries": [
       {
           "name": "org.mcphackers:launchwrapper:1.0",
           "url": "https://mcphackers.github.io/libraries/"
       },
       {
           "name": "org.ow2.asm:asm:9.2",
           "url": "https://repo1.maven.org/maven2/"
       },
       {
           "name": "org.ow2.asm:asm-tree:9.2",
           "url": "https://repo1.maven.org/maven2/"
       },
       {
           "name": "org.json:json:20230311",
           "url": "https://mcphackers.github.io/libraries/"
       },
       {
           "name": "org.mcphackers.rdi:rdi:1.0",
           "url": "https://mcphackers.github.io/libraries/"
       }
   ],
   "mainClass": "org.mcphackers.launchwrapper.Launch",
   "minecraftArguments": "--username ${auth_player_name} --session ${auth_session} --gameDir ${game_directory} --assetsDir ${game_assets}",
   "requires": [
       {
           "uid": "net.minecraft"
       }
   ],
   "formatVersion": 1,
   "name": "LaunchWrapper",
   "uid": "org.mcphackers.launchwrapper",
   "version": "1.0.0"
}

The existing version-specific information about creating a MultiMC instance should apply here (minecraftArguments should be customised as needed, assetIndex and noapplet can be removed for Minecraft 1.6 and onwards etc). The main difference between this and the existing instructions is that the format of the libraries array is different for JSON patches (url is treated like a maven repo).

Save and close the document.

This should produce an instance similar to the attached one. I also edited mmc-pack.json to set dependencyOnly to be true on the LaunchWrapper patch, which prevents disabling it (optional).

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JSON patches for MultiMC instances

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