Resume playback after network interruption should restart at the last played position

[pyby]

Issue type

Incorrect behavior

Description of the problem

During a playback session, a network interruption may occur.
The test was done by enabling the AirPlane mode.

After a while, the "no network" error message appeared. No more buffering UI for the player.
When enabling the network again, the playback resumes from the initial player position, not the last played position.

Environment information

• Library version: 7.1.0
• iOS / tvOS version: Any
• Device: Any (found on iPhone by @svenduvoisin)

Reproducibility

Always reproducible

Steps to reproduce

1. Play a media urn from the beginning.
2. Seek somewhere else and wait that the playback restarts (let's have an example at 24 min of 43 minutes with a VoD).
3. Switch to Airplay mode. Player is buffering.
4. Lock the screen and unlock it. Stay in AirPlane mode.
5. After a while, the "no network" error message appeared.
6. Disable AirPlay mode.

Playback restarts at the SRGLetterboxController initial position (in the example, it restarts at 0 min).
We expect a resume playback at the last played position (in the example, at 24 min).