Fast seek

[StaehliJ]

Description

The goal of this PR is to make an old smooth seeking poc branches. There is a lot of room for improvements.

Changes made

• Add PillarboxLoadControl to optimize loading while smooth seeking.
• Add SmoothProgressTrackerState with new interface to handle seeking ui event ProgressTrackerState.
• Add a show case to enable / disable smooth seeking.

Issues

• While smooth seeking, it may downgrade the video quality and doesn't restore the quality before seeking.
• No user friendly, a public api still have to be made.
• Could work better for HLS with trick play.

Checklist

• Your branch has been rebased onto the main branch.
• APIs have been properly documented (if relevant).
• The documentation has been updated (if relevant).
• New unit tests have been written (if relevant).
• The demo has been updated (if relevant).
• All pull request status checks pass.