[*-extension] Move extension ids to interface level

tweed5-serde-extension/src/main/java/de/siphalor/tweed5/data/extension/api/ReadWriteExtension.java

@@ -14,6 +14,12 @@ import java.util.function.Function;
 
 public interface ReadWriteExtension extends TweedExtension {
 	Class<? extends ReadWriteExtension> DEFAULT = ReadWriteExtensionImpl.class;
+	String EXTENSION_ID = "read-write";
+
+	@Override
+	default String getId() {
+		return EXTENSION_ID;
+	}
 
 	static <T> Consumer<ConfigEntry<T>> entryReaderWriter(
 			TweedEntryReaderWriter<T, ? extends ConfigEntry<T>> entryReaderWriter

tweed5-serde-extension/src/main/java/de/siphalor/tweed5/data/extension/impl/ReadWriteExtensionImpl.java

@@ -38,11 +38,6 @@ public class ReadWriteExtensionImpl implements ReadWriteExtension {
 		this.customEntryDataAccess = context.registerEntryExtensionData(CustomEntryData.class);
 	}
 
-	@Override
-	public String getId() {
-		return "read-write";
-	}
-
 	@Override
 	public void extensionsFinalized() {
 		Collection<TweedExtension> extensions = configContainer.extensions();