SDK / exoplayer

The current logic uses manual array operations to keep track of pending
changes. Modernize this code by using an ArrayDeque and a data class.
This also allows to extend the output stream information in the future.

This also fixes a bug where a position reset accidentally assigns a pending
stream offset instead of keeping the current one.

PiperOrigin-RevId: 511787571
(cherry picked from commit 4e0babdc)