Fix RecordingStream::log implicitly requiring Sized

[teh-cmc]

This makes this kind of code fail to compile:

rec.log("labels", &labels as &dyn crate::AsComponents).unwrap();
rec.log("labels", &labels as &dyn crate::ComponentBatch).unwrap();

[github-actions]

Web viewer built successfully. If applicable, you should also test it:

• I have tested the web viewer

Result	Commit	Link	Manifest
✅	761cc9f	https://rerun.io/viewer/pr/8587	+nightly +main

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[teh-cmc]

@rerun-bot full-check

[github-actions]

Started a full build: https://github.com/rerun-io/rerun/actions/runs/12631792769

[teh-cmc]

I need this, I'm gonna assume this isn't the most controversial thingy.