Add datagen entrypoint hook

Fixes #1128

src/mod/java/org/sinytra/connector/mod/mixin/boot/DatagenModLoaderMixin.java

@@ -0,0 +1,16 @@
+package org.sinytra.connector.mod.mixin.boot;
+
+import net.minecraftforge.data.loading.DatagenModLoader;
+import org.sinytra.connector.mod.ConnectorLoader;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(value = DatagenModLoader.class, remap = false)
+public class DatagenModLoaderMixin {
+    @Inject(method = "begin", at = @At(value = "INVOKE", target = "Lnet/minecraftforge/fml/ModLoader;gatherAndInitializeMods(Lnet/minecraftforge/fml/ModWorkManager$DrivenExecutor;Ljava/util/concurrent/Executor;Ljava/lang/Runnable;)V"))
+    private static void earlyInit(CallbackInfo ci) {
+        ConnectorLoader.load();
+    }
+}

src/mod/java/org/sinytra/connector/mod/mixin/boot/ServerMainMixin.java

@@ -9,7 +9,6 @@
 
 @Mixin(Main.class)
 public abstract class ServerMainMixin {
-
     @Inject(method = "main", at = @At(value = "INVOKE", target = "Lnet/minecraftforge/server/loading/ServerModLoader;load()V"), remap = false)
     private static void earlyInit(CallbackInfo ci) {
         ConnectorLoader.load();

src/mod/resources/connectormod.mixins.json

@@ -12,6 +12,7 @@
     "PlayerListMixin",
     "PoiTypesMixin",
     "TagLoaderMixin",
+    "boot.DatagenModLoaderMixin",
     "item.ForgeHooksMixin",
     "item.ItemStackMixin",
     "item.LateItemStackMixin",