…archical lists (#5362)

### What

This PR introduces a set of helper objects to assist in producing
predictable (and thus stable) `egui::Id` for various objects of our data
model (container, space view, data result, etc.). Since the collapsed
state is in general not shared across different UI area, this PR
proposes a scoping mechanism (implemented with the type system), so the
id for a given item is different depending on, e.g., its appearance in
the blueprint tree or the streams tree.

This improves the collapsed state in hierarchical lists in two ways:
- The collapsed state is now preserved when objects move in the
hierarchy (e.g. a space view is moved from a container to another).
Fixes #5208
- It is now possible to "remotely" change the collapsed state of a given
item, in a given scope.

⚠️⚠️ Demo "Expend all/Collapse all" buttons are included in the
container selection panel, to be reverted before merging.


https://github.com/rerun-io/rerun/assets/49431240/e0d6c47f-59f6-4be1-96d9-03d38d20a580

Blocked by:
- #5371

To address in follow-up PRs:
- ~~fine-tune the DataResult representation such as to ensure sufficient
specificity in case the DataResult appears multiple times in the space
view blueprint sub-tree / cc @Wumpf~~
- add "collapse all"/"expand all" context menu actions
- improve "double-click focus" to uncollapse the focused items

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
[app.rerun.io](https://app.rerun.io/pr/5362/index.html)
* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/5362/index.html?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[app.rerun.io](https://app.rerun.io/pr/5362/index.html?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/5362)
- [Docs
preview](https://rerun.io/preview/250f8e69ccbf28a29980a114ec8fa7ed535c05a8/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/250f8e69ccbf28a29980a114ec8fa7ed535c05a8/examples)
<!--EXAMPLES-PREVIEW-->
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)