Move activity_match() to Protocol\Activity::match()

- With tests

src/Protocol/Activity.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Friendica\Protocol;
+
+/**
+ * Base class for the Activity namespace
+ */
+final class Activity
+{
+	/**
+	 * Compare activity uri. Knows about activity namespace.
+	 *
+	 * @param string $haystack
+	 * @param string $needle
+	 *
+	 * @return boolean
+	 */
+	public function match(string $haystack, string $needle) {
+		return (($haystack === $needle) ||
+		        ((basename($needle) === $haystack) &&
+		         strstr($needle, NAMESPACE_ACTIVITY_SCHEMA)));
+	}
+}