Added support for timesamples in xformOps

[rdeioris]

This patch adds support for timeSamples in xformOps.

GetLocalMatrix() and GetGlobalMatrix() can now extract data from asset like this:

def Xform "Top" (
    prepend references = @./top.geom.usd@
)
{
    float xformOp:rotateX:tilt = 12
    float xformOp:rotateZ:precess.timeSamples = {
        1: 0,
        192: 360,
    }
    float xformOp:rotateZ:spin.timeSamples = {
        1: 0,
        192: 1440,
    }
    double3 xformOp:translate:offset = (0, 0.1, 0)

  
    double3 xformOp:translate:vertical.timeSamples = {
        1: (0, 0.1, 0),
        100: (0, 0.1, 10),
        192: (0, 0.5, 5),
    }

    uniform token[] xformOpOrder = ["xformOp:rotateZ:precess", "xformOp:translate:offset", "xformOp:rotateX:tilt", "xformOp:rotateZ:spin", "xformOp:translate:vertical"]
}

Note that GetLocalMatrix() caching system is now enabled only for t == value::TimeCode::Default()

[syoyo]

Thanks! Let me give some time to review the PR

[syoyo]

described a small review. Others are OK so its ready to merge once that review is resolved.

[rdeioris]

Sorry, not sure to understand, do i need to wait for your review or you already did it and i am missing something? Thanks a lot.

[syoyo]

1. You resolve this pending review(can't find a link to the review) i.e, push a git commit of deleting a comment line
2. After the pending review has been resolved, the PR will be merged.

[syoyo]

Thanks! Merged!