add `clampWhenFinished` to freeze animation on last frame

[hanbollar]

Linking

related to https://discord.com/channels/1137890872688660500/1219366027545149462/1234958188302962739 related to #599

Problem

looping is nice and all, but want to freeze at end of animation instead of reverting back to start

Solution

add as part of animation setup (longer css feature will be different and more robust to mimic https://developer.mozilla.org/en-US/docs/Web/CSS/animation-fill-mode, but this pr is more to match the threejs paradigm, opening a separate issue for the css part: #601

Breaking Change

adding small feature

Notes

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Required to Merge

• [x] PASS - all necessary actions must pass (excluding the auto-skipped ones)

• [x] TEST IN HEADSET - main dev-testing-example and any of the other examples still work as expected

• [x] VIDEO - if this pr changes something visually - post a video here of it in headset-MR and/or on desktop (depending on what it affects) for the reviewer to reference. picture of final state:

  

• [x] TITLE - make sure the pr's title is updated appropriately as it will be used to name the commit on merge

• [x] BREAKING CHANGE

  • DOCUMENTATION: This includes any changes to html tags and their components
  • make a pr in the documentation repo that updates the manual docs to match the breaking change
  • link the pr of the documentation repo here: https://github.com/Volumetrics-io/documentation/pull/50
  • that pr must be approved by @lobau
  • SAMPLES/INDEX.HTML: This includes any changes (html tags or otherwise) that must be done to our landing page submodule as an effect of this pr's updates
  • make a pr in the mrjs landing page repo that updates the landing page to match the breaking change
  • link the pr of the landing page repo here: #pr
  • that pr must be approved by @hanbollar

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[hanbollar]

merging in since it's a very small change - just looks like a lot because code was indented when moved into a loop - commit body on main will reflect the following:

add 'clampWhenFinished' to freeze animation on last frame

- includes moving the setAnimation function calls into a loop over all available animations instead of just the only available one.
- includes addition of more examples in models.html to demo the freeze vs not