Code Generation for TypedKeys (#9233)

Currently includes generated key holder classes for types
used in the Registry Modification API

patches/server/0004-Test-changes.patch

@@ -21,6 +21,45 @@ index ff4d0f970990187e9b46324b5cf051fcc546119f..844eff88c9ad95871900c2d8aa3136b3
  publishing {
      publications.create<MavenPublication>("maven") {
          artifact(tasks.shadowJar)
+diff --git a/src/test/java/io/papermc/paper/registry/RegistryKeyTest.java b/src/test/java/io/papermc/paper/registry/RegistryKeyTest.java
+new file mode 100644
+index 0000000000000000000000000000000000000000..e070aa1bb69859224493d958621389ee757f8752
+--- /dev/null
++++ b/src/test/java/io/papermc/paper/registry/RegistryKeyTest.java
+@@ -0,0 +1,33 @@
++package io.papermc.paper.registry;
++
++import java.util.Optional;
++import java.util.stream.Stream;
++import net.minecraft.core.Registry;
++import net.minecraft.resources.ResourceKey;
++import net.minecraft.resources.ResourceLocation;
++import org.bukkit.support.AbstractTestingBase;
++import org.junit.jupiter.api.BeforeAll;
++import org.junit.jupiter.params.ParameterizedTest;
++import org.junit.jupiter.params.provider.MethodSource;
++
++import static org.junit.jupiter.api.Assertions.assertTrue;
++
++class RegistryKeyTest extends AbstractTestingBase {
++
++    @BeforeAll
++    static void before() throws ClassNotFoundException {
++        Class.forName(RegistryKey.class.getName()); // load all keys so they are found for the test
++    }
++
++    static Stream<RegistryKey<?>> data() {
++        return RegistryKeyImpl.REGISTRY_KEYS.stream();
++    }
++
++    @ParameterizedTest
++    @MethodSource("data")
++    void testApiRegistryKeysExist(final RegistryKey<?> key) {
++        final Optional<Registry<Object>> registry = AbstractTestingBase.REGISTRY_CUSTOM.registry(ResourceKey.createRegistryKey(new ResourceLocation(key.key().asString())));
++        assertTrue(registry.isPresent(), "Missing vanilla registry for " + key.key().asString());
++
++    }
++}
 diff --git a/src/test/java/io/papermc/paper/util/EmptyTag.java b/src/test/java/io/papermc/paper/util/EmptyTag.java
 new file mode 100644
 index 0000000000000000000000000000000000000000..6eb95a5e2534974c0e52e2b78b04e7c2b2f28525