Feat: fps and show_stats for ui.scene

[evnchn]

Motivation

While working on #4820, I noticed that the FPS of NiceGUI's ui.scene is low. I originally though it was Three.js performance issue, but their demo's running at a smooth 120FPS, so I thought what gives?

As it turns out, it's hard-coded to 20FPS (requestAnimationFrame(() => setTimeout(() => render(), 1000 / 20));)

While we're at it, added on the Stats module from Three.js to visualize difference.

Implementation

• Don't hardcode it, accept fps prop
• Add on the Stats module from Three.js to visualize difference.
  • Update npm.json

Progress

• I chose a meaningful title that completes the sentence: "If applied, this PR will..."
• The implementation is complete.
• Pytests have been added (or are not necessary).
• Documentation has been added (or is not necessary).

-> Pytest should be unnecessary, otherwise the testing load may be huge.

[falkoschindler]

Thanks, @evnchn!

Quick question: Am I right to assume that we need to add Stats.js to npm.json?

[evnchn]

Yes. You'd need that to download the file.

See