Add azdata.d.ts for new extensibility APIs (#4247)

* Add azdata.d.ts for new extensibility APIs

* Update azdata typing files for connection API proposal

* Add implementation for azdata module

* Fix build break in agent

src/sql/azdata.d.ts

@@ -0,0 +1,38 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+declare module 'azdata' {
+	import * as vscode from 'vscode';
+
+	// methods
+	export namespace connection {
+
+		/**
+		 * Connection profile primary class
+		 */
+		export class ConnectionProfile {
+			providerId: string;
+			connectionId: string;
+			connectionName: string;
+			serverName: string;
+			databaseName: string;
+			userName: string;
+			password: string;
+			authenticationType: string;
+			savePassword: boolean;
+			groupFullName: string;
+			groupId: string;
+			saveProfile: boolean;
+			azureTenantId?: string;
+
+			static createFrom(options: any[]): ConnectionProfile;
+		}
+
+		/**
+		 * Get the current connection based on the active editor or Object Explorer selection
+		*/
+		export function getCurrentConnection(): Thenable<ConnectionProfile>;
+	}
+}