Initial work merge

[mattmacf98]

This is the initial work for a web based interactivity graph DCC for the new KHR_interactivity spec

[CLAassistant]

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3 out of 5 committers have signed the CLA.

:white_check_mark: petermart
:white_check_mark: hybridherbst
:white_check_mark: pfcDorn
:x: Matthew MacFarquhar
:x: mattmacf98

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