Make all C++ archetypes eager serialized & provide generated update/clear APIs

[Wumpf]

Related

• follow-up of Introduce eager serialization & update/clear APIs in the C++ SDK #8727
• finishes C++ portion of Eager/early serialize of components to arrow in Rust and C++ #7245
• finishes C++ portion of Allow archetypes to clear and/or update existing components #3381
• fixes rerun::Collection borrows data too eagerly, making it very easy to cause segfaults & read of invalid data #7081
  • passing an archetype is no longer a problem
• associated codegen attribute removed in Remove attr.cpp.archetype_eager codegen attribute #8780

What

(see title)
On every archetype in C++ you can now use update_fields & clear_fields!

Commit by commit recommended - most of them are trivial! Outstanding are:

• tensor
  • Because of Split Tensor component into several archetypes #6832 with_dim_names became quite hard. This is covered by a snippet (which I tested manually) but I also added a test now
• video_asset
  • needed to extract video data & media type from the serialized arrow data for a utility method. Nothing too scary, and no large copies involved
• clear
  • needed a new cpp attribute to suppress the =default constructor as this one has its own (previous codegen wasn't as rigorous with default ctors!)

---

• pass complete snippet comparison run locally
• please the different compiler gods and their very individual preferences
• succeed main ci

[Wumpf]

got stuck... what happens if I make this ready for review and then draft it again.

[Wumpf]

nope, only pushing a new commit fixed it.

[github-actions]

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Result	Commit	Link	Manifest
✅	a9f8004	https://rerun.io/viewer/pr/8779	+nightly +main

^{Note: This comment is updated whenever you push a commit.}

[Wumpf]

@rerun-bot full-check

[github-actions]

Started a full build: https://github.com/rerun-io/rerun/actions/runs/12913616811