Rename MessengerGetNotificationReport to MessengerGetNotificationReports

Reset stored services list on destroy

Use CMixTrackServicesWithIdentity instead of CMixTrackServices

- use string for backup params
- start backup with optional params

This reverts commit ff222fa4.

Use stored FileTransfer manager

- When first data arrive, ignore it and add params to the backup
- When following data arrive (that included params), handle it