Syntax highlighting of entity paths and instance paths

[emilk]

What

• Closes Entity Path syntax highlighting #4598

Adds basic syntax highlighting to patsh. Slashes and brackets are in a fixed bright-white color, while the text uses the color appropriate for the widget it is in (labels are dimmer than button, for instance).

For labels this produces a lot of contrast:

For buttons, not so much:

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 newly built examples: app.rerun.io
  • Using examples from latest main build: app.rerun.io
  • Using full set of examples from nightly build: app.rerun.io
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG

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[Wumpf]

move instance path to where?

aren't these making re_ui a lot less lightweight?

[emilk]

move instance path to where?

It feels like it belongs in a more low-level crate, like re_types

aren't these making re_ui a lot less lightweight?

Yes. The alternative is to create yet another crate, or add more feature flags, and both kind of sucks.

[Wumpf]

quite subtle here as well hmm

[Wumpf]

neat! A bit too subtle for my taste, but clear improvement

[Wumpf]

is it actually syntax highlighting or just "make this an egui text"? ToLayoutJob might be just as appropriate

[emilk]

Discussed live: we'll probably use this trait for more syntax highlighting stuff in the future, and that's what you want to search for in the code. Still, we can revisit the name later if we want to.