Double-clicking an entity in the blueprint & time panels focuses the 3D camera on it

[Wumpf]

What

• Fixes viewer: double clicking an entity in the spatial view should put it into focus #918
• Fixes viewer: double clicking an entity in the blueprint should put it into focus #917

This PR introduces on-the-fly determined per-entity bounding boxes and unifies a lot of behavior under the hood: A double click of a hovered item (pretty much everywhere) causes now a "focused" event for that item. Focuses are right now set on the viewer context for a single frame, so each part of the viewer can react on it as it pleases. The 3D Space view reacts by focusing the camera on the entity (using the new bounding box) and tracks cameras.
Tracking of entities has been unified - originally this PR tracked entities as well, but I found this a bit too confusing for this action, we should instead have something more explicit (this was disabled in 86ddf0d so it's easy to get it back).

Screen.Recording.2024-01-12.at.16.05.53.mov

Tradeoffs:

• can't focus on instances
  -> before focused on 3D positions (without knowing anything about the object under it) now focusing on entities; different behavior, sometimes worse, sometimes better
  -> note that tracking an instance rarely what you want here (e.g. point instance ids vary widely)
• tracking an entity is not always what you want -> disabled it
  • it's very hard to tell that we're tracking something, can sometimes be surprising
• Alternative design of focus: Send a focus event to space views that should be interested in it. This makes would unify the dispatching code for this which is nicer going forward. But for the moment it was just a lot easier to implement it the way I did. I'm fairly sure though about making focus not sticky in the global state since this way we'd end up with two levels of selection.

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[Wumpf]

when testing one last time on the web I found that camera tracking lags behind, so this regressed

[emilk]

I think you should also try a scene with a lot of entities to see that perf hasn't regressed

[Wumpf]

added a primitive benchmark that adds lots of entitites. No measurable regression, but it's shocking how few entities we can handle