Added Sieve extension rfc6134 partial

dev/Sieve/Extensions/rfc6134.js

@@ -0,0 +1,32 @@
+/**
+ * https://tools.ietf.org/html/rfc6134
+ */
+
+import {
+	GrammarStringList,
+	GrammarTest
+} from 'Sieve/Grammar';
+
+/**
+ * https://datatracker.ietf.org/doc/html/rfc6134#section-2.7
+ */
+export class ValidExtListTest extends GrammarTest
+{
+	constructor()
+	{
+		super();
+		this.ext_list_names = new GrammarStringList;
+	}
+
+	get require() { return 'foreverypart'; }
+
+	toString()
+	{
+		return 'valid_ext_list ' + this.ext_list_names;
+	}
+
+	pushArguments(args)
+	{
+		this.ext_list_names = args.pop();
+	}
+}