Add KHR_interactivity draft

[lexaknyazev]

Rendered version: https://github.com/KhronosGroup/glTF/blob/interactivity/extensions/2.0/Khronos/KHR_interactivity/Specification.adoc

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_{Edited by javagl: For those looking at this PR in the future, the link is now https://github.com/KhronosGroup/glTF/blob/main/extensions/2.0/Khronos/KHR_interactivity/Specification.adoc , with the exact version from this PR being https://github.com/KhronosGroup/glTF/blob/b11fb686120f822afc85b89960ab8e7e8f51b026/extensions/2.0/Khronos/KHR_interactivity/Specification.adoc}

[bhouston]

Great work! What sections are next? Also what could we release as a draft extension for SIGGRAPH 2023?

[robertdorn83]

@lexaknyazev

can you add some pointer samples to get Ref-Objects via json pointers? like pointer/get > /animations/0, to get the animation reference.

and: is "/animations/0" the correct format to get the reference from animation-index 0? or would it be "/animations/0/"?

[emackey]

Can we merge or rebase main here?

[lexaknyazev]

Can we merge or rebase main here?

That will happen automatically because there are no merge conflicts.

[emackey]

That will happen automatically because there are no merge conflicts.

Sure, but I'm trying to see what will happen to the CI itself, there are several CI workflow diffs here.

[lexaknyazev]

Sure, but I'm trying to see what will happen to the CI itself, there are several CI workflow diffs here.

The workflows run successfully and produce correct outputs, see the Checks tab.

[emackey]

I checked the CI outputs, and this appears safe to merge. I have not reviewed the Interactivity spec itself in fine-grain detail, but many others here have been doing that for many months. A discussion earlier today revealed no objections to merging, with the understanding that further refinements are likely as a wider audience begins to embrace this.