Update to latest Fabric

- Overhaul model loading to work with the new API. This allows for
   using the emissive texture system in a more generic way, which is
   nice!

 - Convert some of our custom models to use Fabric's model hooks (i.e.
   emitItemQuads). We don't make use of this right now, but might be
   useful for rendering tools with enchantment glints.

   Note this does /not/ change any of the turtle block entity rendering
   code to use Fabric/Forge's model code. This will be a change we want
   to make in the future.

 - Some cleanup of our config API. This fixes us printing lots of
   warnings when creating a new config file on Fabric (same bug also
   occurs on Forge, but that's a loader problem).

 - Fix a few warnings

projects/core/src/test/java/dan200/computercraft/core/ComputerTestDelegate.java

@@ -4,6 +4,7 @@
 
 package dan200.computercraft.core;
 
+import com.google.common.base.Splitter;
 import dan200.computercraft.api.filesystem.WritableMount;
 import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.LuaException;
@@ -346,10 +347,10 @@ public class ComputerTestDelegate {
                 var details = (Map<?, ?>) entry.getValue();
                 var def = (String) details.get("definition");
 
-                var parts = name.split("\0");
+                var parts = Splitter.on('\0').splitToList(name);
                 var builder = root;
-                for (var i = 0; i < parts.length - 1; i++) builder = builder.get(parts[i]);
-                builder.runs(parts[parts.length - 1], def, () -> {
+                for (var i = 0; i < parts.size() - 1; i++) builder = builder.get(parts.get(i));
+                builder.runs(parts.get(parts.size() - 1), def, () -> {
                     // Run it
                     lock.lockInterruptibly();
                     try {