Simple Shadow Copy Creation for Backup

There are a number of different types of shadow copy a requester can create. However, for most backup applications, you would do the following:

1. Call IVssBackupComponents::SetContext with a context of VSS_CTX_BACKUP.
2. Call IVssBackupComponents::GatherWriterMetadata to initialize communication with writers.
3. Call IVssBackupComponents::AddComponent to add file and database components to the backup.
4. Call IVssBackupComponents::StartSnapshotSet to initialize the shadow copy mechanism.
5. Call IVssBackupComponents::AddToSnapshotSet to include volumes in the shadow copy.
6. Call IVssBackupComponents::PrepareForBackup to notify writers of backup operations.