Enhance SessionManager with PeriodUid

**As a user / integrator** I want session detection work even if the same MediaItem is inside the playlist.

# Acceptance criteria

- Same media item in the playlist triggers new session.

## Hints

```kotlin
 val windowIndex = eventTime.windowIndex
 eventTime.timeline.getWindow(windowIndex, window)
 val periodUid = eventTime.timeline.getUidOfPeriod(window.firstPeriodIndex)
```

# Tasks

- [ ] ...