RB: Force SampleGridoModel.MATCH_EDGES descale and rescale calls

[LightArrowsEXE]

Currently with the following code, sample_grid_model is effectively applied twice, which introduces additional shifts and other issues:

    edges = RescaleBuilder(clip).descale(
        Lanczos(2),
        1280,
        720,
    )
    centers = RescaleBuilder(clip).descale(
        Lanczos(2, sample_grid_model=SampleGridModel.MATCH_CENTERS),
        1280,
        720,
    )

	Descaled clip	Rescaled clip
MATCH_EDGES
MATCH_CENTERS

Since the descale/rescale calls in RescaleBuilder already obtain these values from ScalingArgs.from_args, we can apply MATCH_EDGES at these steps instead. Ideally we don't want to mutate the Kernel object though, so I simply added a private wrapper to deal with this for the time being. There's probably a better solution out there, which is what I hope to uncover through this PR too. CC: @Ichunjo

Note: This issue is possibly also a problem in vsscale's rescaling functions.