Codify how to group our imports

[emilk]

I'll actually apply it once these PRs are merged:

• RRD footers 1: framing #12044
• RRD footers 2: RRD manifests #12047
• RRD footers 3: encoding/decoding manifests #12048

[github-actions]

Web viewer built successfully.

Result	Commit	Link	Manifest
✅	8ca9851	https://rerun.io/viewer/pr/12063	+nightly +main

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