Move trait SizeBytes to new crate re_byte_size

[emilk]

This is so that I can move fn arrow_ui (which depend on SizeBytes) into re_ui, as part of improved testing of it before migrating it to arrow1.

And re_byte_size sounds nicer than re_sizes_bytes. Maybe we should rename the trait to ByteSize too.

[github-actions]

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Result	Commit	Link	Manifest
✅	42fe3af	https://rerun.io/viewer/pr/8544	+nightly +main

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