Add datapack registration lifecycle event (#11804)

paper-server/src/main/java/io/papermc/paper/datapack/PaperDiscoveredDatapack.java

@@ -0,0 +1,69 @@
+package io.papermc.paper.datapack;
+
+import com.google.common.collect.ImmutableMap;
+import io.papermc.paper.adventure.PaperAdventure;
+import io.papermc.paper.world.flag.PaperFeatureFlagProviderImpl;
+import java.util.Map;
+import java.util.Set;
+import net.kyori.adventure.text.Component;
+import net.minecraft.server.packs.repository.Pack;
+import net.minecraft.server.packs.repository.PackSource;
+import org.bukkit.FeatureFlag;
+import org.jspecify.annotations.NullMarked;
+
+@NullMarked
+public class PaperDiscoveredDatapack implements DiscoveredDatapack {
+
+    private static final Map<PackSource, DatapackSource> PACK_SOURCES;
+    static {
+        PACK_SOURCES = ImmutableMap.<PackSource, DatapackSource>builder()
+            .put(PackSource.DEFAULT, DatapackSource.DEFAULT)
+            .put(PackSource.BUILT_IN, DatapackSource.BUILT_IN)
+            .put(PackSource.FEATURE, DatapackSource.FEATURE)
+            .put(PackSource.WORLD, DatapackSource.WORLD)
+            .put(PackSource.SERVER, DatapackSource.SERVER)
+            .put(PluginPackSource.INSTANCE, DatapackSource.PLUGIN)
+            .buildOrThrow();
+    }
+
+    private final Pack pack;
+
+    PaperDiscoveredDatapack(final Pack pack) {
+        this.pack = pack;
+    }
+
+    @Override
+    public String getName() {
+        return this.pack.getId();
+    }
+
+    @Override
+    public Component getTitle() {
+        return PaperAdventure.asAdventure(this.pack.getTitle());
+    }
+
+    @Override
+    public Component getDescription() {
+        return PaperAdventure.asAdventure(this.pack.getDescription());
+    }
+
+    @Override
+    public boolean isRequired() {
+        return this.pack.isRequired();
+    }
+
+    @Override
+    public Datapack.Compatibility getCompatibility() {
+        return Datapack.Compatibility.valueOf(this.pack.getCompatibility().name());
+    }
+
+    @Override
+    public Set<FeatureFlag> getRequiredFeatures() {
+        return PaperFeatureFlagProviderImpl.fromNms(this.pack.getRequestedFeatures());
+    }
+
+    @Override
+    public DatapackSource getSource() {
+        return PACK_SOURCES.computeIfAbsent(this.pack.location().source(), source -> new DatapackSourceImpl(source.toString()));
+    }
+}