Expose additional information about decoded frames in the viewer

[Wumpf]

What

Minimized by default.

Originally, I wanted to add some more information from the get-go like i/idr/p/b-frame type but turns out we don't really have all that much information around today for sure - a big part of this is that typically just pass in chunks to decoder and get 0-1 frames out for each chunk (my current understand is that it could be 0-n, but n>1 typically doesn't make sense because a single mp4 sample has a single timestamp!). Meaning we typically don't maintain the chunk/frame relationship.
However, this adjusted structure should make it easy to expose optional fields on FrameInfo to forward all sort of things

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
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  • Using examples from latest main build: rerun.io/viewer
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[emilk]

great!

[emilk]

yes, this would be nice! :)