Chained mod target overlays

- Mod targets list an ordered overlay chain; later overlays replace earlier ones and earlier source replacements apply to inherited files
- Forge and NeoForge metadata take their loader version range from the target
- The Fabric permissions library is bundled only for targets that declare it
- Dropped the 1.21.1 mods.toml copies that only differed in the loader range

adapters/forge/src/main/resources/META-INF/mods.toml

@@ -1,5 +1,5 @@
 modLoader = "javafml"
-loaderVersion = "[66,67)"
+loaderVersion = "${loaderRange}"
 license = "GPL-3.0"
 issueTrackerURL = "https://github.com/VolmitSoftware/Iris/issues"
 
@@ -16,7 +16,7 @@ logoFile = "assets/irisworldgen/icon.png"
 [[dependencies.irisworldgen]]
 modId = "forge"
 mandatory = true
-versionRange = "[66,67)"
+versionRange = "${loaderRange}"
 ordering = "NONE"
 side = "BOTH"