KeyframeTrack: Improve docs and subtype ctors.

[trusktr]

Description

Adds a few small details to docs for KeyframeTrack and its subtypes. Also expresses the lack of interpolation parameters for Boolean and String keyframe tracks in their class constructor.

This contribution is funded by Lume - 3D HTML elements

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize dev	Filesize PR	Diff
675.7 kB (167.5 kB)	675.7 kB (167.5 kB)	+27 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

Filesize dev	Filesize PR	Diff
454.8 kB (109.8 kB)	454.8 kB (109.8 kB)	+0 B

[Mugen87]

The unit tests of BooleanKeyframeTrack and StringKeyframeTrack still apply the interpolation to their ctor.

[trusktr]

e2e snapshot tests failed on the last commit for some reason, but in that last commit I didn't change code, I only removed the unused parts of the unit tests. Seems like a fluke.

I can't get the e2e tests to run locally:

$ npm run test-e2e

> three@0.164.1 test-e2e
> node test/e2e/puppeteer.js

file:///Users/trusktr/src/mrdoob+three.js/node_modules/@puppeteer/browsers/lib/esm/launch.js:301
                reject(new Error([
                       ^

Error: Failed to launch the browser process!


TROUBLESHOOTING: https://pptr.dev/troubleshooting

    at Interface.onClose (file:///Users/trusktr/src/mrdoob+three.js/node_modules/@puppeteer/browsers/lib/esm/launch.js:301:24)
    at Interface.emit (node:events:526:35)
    at Interface.close (node:internal/readline/interface:527:10)
    at Socket.onend (node:internal/readline/interface:253:10)
    at Socket.emit (node:events:526:35)
    at endReadableNT (node:internal/streams/readable:1376:12)
    at process.processTicksAndRejections (node:internal/process/task_queues:82:21)

Node.js v20.6.1