check for encoded components (#18231)

* check for encoded components

* address comments

* relocate and simplify test

* move encodeUrl to notebookLinkHandler

* added comments

* add containsEncodedUri to network.ts

src/sql/base/common/network.ts

@@ -0,0 +1,14 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+/**
+* Checks if the specified URL is already URI-encoded by checking if there are any unencoded reserved URI component characters
+* (such as ?, =, &, /, etc.) in the URL. See https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/decodeURIComponent for more details.
+* @returns true if the URL contains encoded URI component reserved characters
+*/
+export function containsEncodedUriComponentReservedCharacters(url: string): boolean {
+	// ie ?,=,&,/ etc
+	return (decodeURI(url) !== decodeURIComponent(url));
+}