Add a logout command and menu item

This will only show if you have authentication enabled.

This has e2e tests but are currently disabled and need to be fixed.

Index: code-server/lib/vscode/src/vs/base/common/product.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/base/common/product.ts
+++ code-server/lib/vscode/src/vs/base/common/product.ts
@@ -34,6 +34,7 @@ export interface IProductConfiguration {
 	readonly codeServerVersion?: string
 	readonly rootEndpoint?: string
 	readonly updateEndpoint?: string
+	readonly logoutEndpoint?: string
 
 	readonly version: string;
 	readonly date?: string;
Index: code-server/lib/vscode/src/vs/server/node/serverEnvironmentService.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/server/node/serverEnvironmentService.ts
+++ code-server/lib/vscode/src/vs/server/node/serverEnvironmentService.ts
@@ -13,6 +13,7 @@ import { IEnvironmentService, INativeEnv
 export const serverOptions: OptionDescriptions<ServerParsedArgs> = {
 	/* ----- code-server ----- */
 	'disable-update-check': { type: 'boolean' },
+	'auth': { type: 'string' },
 
 	/* ----- server setup ----- */
 
@@ -88,6 +89,7 @@ export const serverOptions: OptionDescri
 export interface ServerParsedArgs {
 	/* ----- code-server ----- */
 	'disable-update-check'?: boolean;
+	'auth'?: string
 
 	/* ----- server setup ----- */
 
Index: code-server/lib/vscode/src/vs/server/node/webClientServer.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/server/node/webClientServer.ts
+++ code-server/lib/vscode/src/vs/server/node/webClientServer.ts
@@ -287,6 +287,7 @@ export class WebClientServer {
 				productConfiguration: <Partial<IProductConfiguration>>{
 					rootEndpoint: base,
 					updateEndpoint: !this._environmentService.args['disable-update-check'] ? base + '/update/check' : undefined,
+					logoutEndpoint: this._environmentService.args['auth'] ? base + '/logout' : undefined,
 					extensionsGallery: {
 						...this._productService.extensionsGallery,
 						'resourceUrlTemplate': this._webExtensionResourceUrlTemplate ? this._webExtensionResourceUrlTemplate.with({
Index: code-server/lib/vscode/src/vs/workbench/browser/client.ts
===================================================================
--- code-server.orig/lib/vscode/src/vs/workbench/browser/client.ts
+++ code-server/lib/vscode/src/vs/workbench/browser/client.ts
@@ -1,11 +1,15 @@
 import { Disposable } from 'vs/base/common/lifecycle';
 import { localize } from 'vs/nls';
+import { MenuId, MenuRegistry } from 'vs/platform/actions/common/actions';
+import { CommandsRegistry } from 'vs/platform/commands/common/commands';
 import { ILogService } from 'vs/platform/log/common/log';
 import { INotificationService, Severity } from 'vs/platform/notification/common/notification';
 import { IProductService } from 'vs/platform/product/common/productService';
 import { IStorageService, StorageScope, StorageTarget } from 'vs/platform/storage/common/storage';
 
 export class CodeServerClient extends Disposable {
+	static LOGOUT_COMMAND_ID = 'code-server.logout';
+
 	constructor (
 		@ILogService private logService: ILogService,
 		@INotificationService private notificationService: INotificationService,
@@ -82,6 +86,10 @@ export class CodeServerClient extends Di
 		if (this.productService.updateEndpoint) {
 			this.checkUpdates(this.productService.updateEndpoint)
 		}
+
+		if (this.productService.logoutEndpoint) {
+			this.addLogoutCommand(this.productService.logoutEndpoint);
+		}
 	}
 
 	private checkUpdates(updateEndpoint: string) {
@@ -133,4 +141,25 @@ export class CodeServerClient extends Di
 
 		updateLoop();
 	}
+
+	private addLogoutCommand(logoutEndpoint: string) {
+		CommandsRegistry.registerCommand(CodeServerClient.LOGOUT_COMMAND_ID, () => {
+			const logoutUrl = new URL(logoutEndpoint, window.location.href);
+			// Cookies must be set with absolute paths and must use the same path to
+			// be unset (we set it on the root) so send the relative root and the
+			// current href so the backend can derive the absolute path to the root.
+			logoutUrl.searchParams.set('base', this.productService.rootEndpoint || ".");
+			logoutUrl.searchParams.set('href', window.location.href);
+			window.location.assign(logoutUrl);
+		});
+
+		for (const menuId of [MenuId.CommandPalette, MenuId.MenubarHomeMenu]) {
+			MenuRegistry.appendMenuItem(menuId, {
+				command: {
+					id: CodeServerClient.LOGOUT_COMMAND_ID,
+					title: localize('logout', "Sign out of {0}", 'code-server'),
+				},
+			});
+		}
+	}
 }