REST: Mark TransformHandler as not needing write access

This doesn't write anything to the wiki, it just transforms from
wikitext to HTML and vice versa.

Bug: T367625
Change-Id: Ica314f7fe04fc5d93bb96d16a07067e630a335a9

includes/Rest/Handler/TransformHandler.php

@@ -54,6 +54,13 @@ class TransformHandler extends ParsoidHandler {
 				ParamValidator::PARAM_REQUIRED => false, ], ];
 	}
 
+	/**
+	 * @inheritDoc
+	 */
+	public function needsWriteAccess() {
+		return false;
+	}
+
 	public function checkPreconditions() {
 		// NOTE: disable all precondition checks.
 		// If-(not)-Modified-Since is not supported by the /transform/ handler.