stage2/ml9: Fix merging of provided services into KFF

With kotlinx-metadata-jvm being promoted to stable in Kotlin 2.0, the
kotlin-reflect library now relies on a new service ([1]), the services
file for which wasn't yet present in older KFF versions.
And with the Java module system, which ModLauncher uses, merely merging
the service file from the newer Kotlin isn't enough, we also need to
merge them into KFF's module descriptor.

[1]:
https://github.com/JetBrains/kotlin/blob/4c61b7118f23a090a764a3aa07e4291e50210771/libraries/kotlinx-metadata/jvm/resources/META-INF/services/kotlin.metadata.internal.extensions.MetadataExtensions

Author: Johni0702

stage2/modlauncher9/src/main/java/gg/essential/loader/stage2/DescriptorRewritingJarMetadata.java

@@ -6,12 +6,17 @@
 import gg.essential.loader.stage2.util.Lazy;
 
 import java.lang.module.ModuleDescriptor;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
 
 /**
  * Re-creates the {@link #descriptor()} with an updated {@link SecureJar#getPackages() package list}.
  * This is needed when one adds classes (even internal ones) to a {@link SecureJar} in previously non-existent packages
  * because the module system needs to know about all packages because ModLauncher will use that package list to build
  * a lookup table.
+ * Also updates the provided services with the ones from the new meta.
  */
 public class DescriptorRewritingJarMetadata implements JarMetadata {
     private final JarMetadata delegate;
@@ -47,7 +52,13 @@ public ModuleDescriptor descriptor() {
                 }
                 org.uses().forEach(builder::uses);
             }
-            org.provides().forEach(builder::provides);
+            Map<String, List<String>> orgProvides = org.provides()
+                .stream().collect(Collectors.toMap(ModuleDescriptor.Provides::service, ModuleDescriptor.Provides::providers));
+            Map<String, List<String>> newProvides = newPkgsMeta.descriptor().provides()
+                .stream().collect(Collectors.toMap(ModuleDescriptor.Provides::service, ModuleDescriptor.Provides::providers));
+            Map<String, List<String>> mergedProvides = new HashMap<>(orgProvides);
+            mergedProvides.putAll(newProvides);
+            mergedProvides.forEach(builder::provides);
             org.mainClass().ifPresent(builder::mainClass);
             this.descriptor = builder.build();
         }