Use SequencerByKey to sequence operations of the same set of scopes (#192638)

The idea here is... if a token is currently being refreshed, well then getting a token of those scopes should wait for that to finish.

Core has a really nice `SequencerByKey` for exactly this kind of thing, and so I've stolen that and started to organize the code with a `common` folder.

Oh, I also noticed we were sorting twice and fixed that to only sort once.

ref https://github.com/microsoft/vscode/issues/186693

extensions/microsoft-authentication/src/common/async.ts

@@ -0,0 +1,49 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { Disposable } from 'vscode';
+
+export class SequencerByKey<TKey> {
+
+	private promiseMap = new Map<TKey, Promise<unknown>>();
+
+	queue<T>(key: TKey, promiseTask: () => Promise<T>): Promise<T> {
+		const runningPromise = this.promiseMap.get(key) ?? Promise.resolve();
+		const newPromise = runningPromise
+			.catch(() => { })
+			.then(promiseTask)
+			.finally(() => {
+				if (this.promiseMap.get(key) === newPromise) {
+					this.promiseMap.delete(key);
+				}
+			});
+		this.promiseMap.set(key, newPromise);
+		return newPromise;
+	}
+}
+
+export class IntervalTimer extends Disposable {
+
+	private _token: any;
+
+	constructor() {
+		super(() => this.cancel());
+		this._token = -1;
+	}
+
+	cancel(): void {
+		if (this._token !== -1) {
+			clearInterval(this._token);
+			this._token = -1;
+		}
+	}
+
+	cancelAndSet(runner: () => void, interval: number): void {
+		this.cancel();
+		this._token = setInterval(() => {
+			runner();
+		}, interval);
+	}
+}