`@remotion/media`: Make `<Video>` and `<Audio>` a true `<Sequence>` and inherit timeline rendering behavior (#7228)

* refactor timeline rendering

* cool

* make it make sense

* ok

* just wanted to say it

* memo

* call it experimental controls

* Update NewVideo.tsx

* cool

* fix issues reported

* fix e2e selectors to ignore disabled expand buttons

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

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Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>