feat(backup): enable WindowsVss Backup (#15934)

Closes #14803.
Reference Pull Request : #14891 

Lets you set the 'WindowsVss' option when you create a new backup plan like this:

```ts
const plan = new BackupPlan(stack, 'Plan', {
  windowsVss: true,
});
```
----
*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: cokia

packages/@aws-cdk/aws-backup/README.md

@@ -82,6 +82,17 @@ const plan = backup.BackupPlan.daily35DayRetention(this, 'Plan', myVault); // Us
 plan.addRule(backup.BackupPlanRule.monthly1Year(otherVault)); // Use `otherVault` for this specific rule
 ```
 
+You can [backup](https://docs.aws.amazon.com/aws-backup/latest/devguide/windows-backups.html)
+VSS-enabled Windows applications running on Amazon EC2 instances by setting the `windowsVss`
+parameter to `true`. If the application has VSS writer registered with Windows VSS,
+then AWS Backup creates a snapshot that will be consistent for that application.
+
+```ts
+const plan = new backup.BackupPlan(this, 'Plan', {
+  windowsVss: true,
+});
+```
+
 ## Backup vault
 
 In AWS Backup, a *backup vault* is a container that you organize your backups in. You can use backup

packages/@aws-cdk/aws-backup/lib/plan.ts

@@ -43,6 +43,15 @@ export interface BackupPlanProps {
    * @default - use `addRule()` to add rules
    */
   readonly backupPlanRules?: BackupPlanRule[];
+
+  /**
+   * Enable Windows VSS backup.
+   *
+   * @see https://docs.aws.amazon.com/aws-backup/latest/devguide/windows-backups.html
+   *
+   * @default false
+   */
+  readonly windowsVss?: boolean;
 }
 
 /**
@@ -124,6 +133,7 @@ export class BackupPlan extends Resource implements IBackupPlan {
 
     const plan = new CfnBackupPlan(this, 'Resource', {
       backupPlan: {
+        advancedBackupSettings: this.advancedBackupSettings(props),
         backupPlanName: props.backupPlanName || id,
         backupPlanRule: Lazy.any({ produce: () => this.rules }, { omitEmptyArray: true }),
       },
@@ -140,6 +150,18 @@ export class BackupPlan extends Resource implements IBackupPlan {
     }
   }
 
+  private advancedBackupSettings(props: BackupPlanProps) {
+    if (!props.windowsVss) {
+      return undefined;
+    }
+    return [{
+      backupOptions: {
+        WindowsVSS: 'enabled',
+      },
+      resourceType: 'EC2',
+    }];
+  }
+
   /**
    * Adds a rule to a plan
    *

packages/@aws-cdk/aws-backup/test/plan.test.ts

@@ -70,6 +70,36 @@ test('create a plan and add rules', () => {
   });
 });
 
+test('create a plan and add rules - add BackupPlan.AdvancedBackupSettings.BackupOptions', () => {
+  const vault = new BackupVault(stack, 'Vault');
+  const otherVault = new BackupVault(stack, 'OtherVault');
+
+  // WHEN
+  const plan = new BackupPlan(stack, 'Plan', {
+    windowsVss: true,
+    backupVault: vault,
+    backupPlanRules: [
+      new BackupPlanRule({
+        completionWindow: Duration.hours(2),
+        startWindow: Duration.hours(1),
+        scheduleExpression: events.Schedule.cron({
+          day: '15',
+          hour: '3',
+          minute: '30',
+        }),
+        moveToColdStorageAfter: Duration.days(30),
+      }),
+    ],
+  });
+  plan.addRule(BackupPlanRule.monthly5Year(otherVault));
+
+  Template.fromStack(stack).hasResourceProperties('AWS::Backup::BackupPlan', {
+    BackupPlan: {
+      AdvancedBackupSettings: [{ BackupOptions: { WindowsVSS: 'enabled' }, ResourceType: 'EC2' }],
+    },
+  });
+});
+
 test('daily35DayRetention', () => {
   // WHEN
   BackupPlan.daily35DayRetention(stack, 'D35');