[three] Make KeyframeTrack interpolation optional (#29692)
[three] Make KeyframeTrack interpolation optional (#29692)


dsebastien/DefinitelyTyped,mcliment/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,magny/DefinitelyTyped,markogresak/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,magny/DefinitelyTyped