ui: Track search & full track virtualization

[stevegolton]

This WIP PR implements two new features:

• Full virtualization of tracks (no DOM nodes drawn at all for offscreen tracks).
• A track search feature, that works just like Ctrl+F but still works on tracks that are not present in the DOM.

For now, this PR has a few major flaws:

• The track search takes over the hotkey Ctrl+F/Cmd+F, and only searches track names (and thus offers less functionality). We need to find a way to steer users towards this track search without taking over the native browser DOM search.
• The track search is in yet another search box - separate to the omnibox, and the track filter box. This is too many boxes - we need to combine them.
• Every frame the entire tree of tracks is still traversed. We're leaving performance on the table.

[github-actions]

🎨 Perfetto UI Build

✅ UI build is ready: https://storage.googleapis.com/perfetto-ci-artifacts/gh-21207111621-1-ui/ui/index.html