Update to latest egui

[emilk]

What

Uses the latest egui containing this gem:

• Add Context::request_discard for multi-pass layouts emilk/egui#5059

So far request_discard (running a second pass) is only used in these situations:

• For when a Grid first shows up
• When an egui_table first shows up
• When asked to auto-size an egui_table row

Of course, running a second pass has some costs. Luckily, we already execute our most expensive stuff (the viewport) last, and so we can easily early-out from things like point cloud upload/rendering, as shown in this puffin-capture of a frame with two passes in it:

NOTE: this flamegraph is of a DEBUG build - the point is not the relative times, but that pass 0 becomes very cheap, if the request_discard is called from one of the non-viewport panels (e.g. the selection panel).

There might still be cases where we do expensive stuff twice, e.g. if something calls request_discard in a space view tooltip.

If we come to regret this, we can disable all second passes by setting egui::Options::max_passes to 1.

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using examples from latest main build: rerun.io/viewer
  • Using full set of examples from nightly build: rerun.io/viewer
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG
• If applicable, add a new check to the release checklist!
• If have noted any breaking changes to the log API in CHANGELOG.md and the migration guide

• PR Build Summary
• Recent benchmark results
• Wasm size tracking

To run all checks from main, comment on the PR with @rerun-bot full-check.

[Wumpf]

sounds promising!