Backup-SqlDscDatabase: Add new command for database backups (#2366)

Author: johlju

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Added public command `Backup-SqlDscDatabase` to perform database backups using
+  SMO's `Microsoft.SqlServer.Management.Smo.Backup` class. Supports full,
+  differential, and transaction log backups with options for compression,
+  copy-only, checksum, and retention. Accepts both Server and Database objects
+  via pipeline
+  ([issue #2365](https://github.com/dsccommunity/SqlServerDsc/issues/2365)).
 - `Set-SqlDscServerPermission`
   - Added integration tests for negative test scenarios including invalid
     permission names and non-existent principals.

azure-pipelines.yml

@@ -341,6 +341,7 @@ stages:
                   'tests/Integration/Commands/ConvertFrom-SqlDscDatabasePermission.Integration.Tests.ps1'
                   'tests/Integration/Commands/New-SqlDscDatabase.Integration.Tests.ps1'
                   'tests/Integration/Commands/New-SqlDscDatabaseSnapshot.Integration.Tests.ps1'
+                  'tests/Integration/Commands/Backup-SqlDscDatabase.Integration.Tests.ps1'
                   'tests/Integration/Commands/Resume-SqlDscDatabase.Integration.Tests.ps1'
                   'tests/Integration/Commands/Suspend-SqlDscDatabase.Integration.Tests.ps1'
                   'tests/Integration/Commands/Get-SqlDscCompatibilityLevel.Integration.Tests.ps1'