Add support for Draco encoding

[alexchuber]

Add support for compressing meshes with Draco encoding. Introduces:

• DracoEncoder class, with same usage pattern as DracoDecoder
• Encoding options per mesh, with several new types to support this
• New worker function and EncodeMesh() function in dracoCompressionWorker
• Type files, separated by DracoEncoder and DracoDecoder, to avoid cluttering dracoCompressionWorker (while still avoiding cyclical dependencies)

I don't feel particularly content with dracoCompressionWorker-- both because encoding/decoding are present in the same file, and becauase I'm not sure that the worker functions must be separate. Please let me know of better ideas for this :)

[bjsplat]

Please make sure to label your PR with "bug", "new feature" or "breaking change" label(s).
To prevent this PR from going to the changelog marked it with the "skip changelog" label.

[bjsplat]

Please make sure to label your PR with "bug", "new feature" or "breaking change" label(s).
To prevent this PR from going to the changelog marked it with the "skip changelog" label.

[bjsplat]

Please make sure to label your PR with "bug", "new feature" or "breaking change" label(s).
To prevent this PR from going to the changelog marked it with the "skip changelog" label.

[bjsplat]

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[bjsplat]

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[bjsplat]

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[sebavan]

I like the intent and feature !!! I ll let @RaananW and @bghgary comment more on it

[sebavan]

cc @bghgary and I ll do the final review :-)

[sebavan]

The PR will wait some checks with @RaananW next year :-)