Remove multiplier from resource docs, add it instead as an extra first dimension in descriptor shape

[jwlodek]

Per discussion today, it was decided that in order to keep the dimensionality of shape in the event descriptor consistent, that the multiplier should be added there as the first dimension. So for example in the case of two detectors w/ x-y dimensions of 10x10, with one collecting a single frame per acq, and one collecting 5, we would have

shape: (1, 10, 10)

and

shape: (5, 10, 10)

respectively in the descriptor. Since this tells you the multiplier, and you can fetch this information given a resource doc by looking back at the associated descriptor, the multiplier field can be removed from the resource doc creation.

[jwlodek]

@coretl @genematx @danielballan