Option to delay scale_factors downsampling along Z dimension for 3D images

[keller-mark]

Is your feature request related to a problem? Please describe.

Given 3D image with original TCZYX shape [ 1, 12, 194, 3181, 4045 ], I want the following multiscales:

• 0: [ 1, 12, 194, 3181, 4045 ]
• 1: [ 1, 12, 194, 1590, 2022 ]
• 2: [ 1, 12, 194, 795, 1011 ]
• 3: [ 1, 12, 194, 398, 506 ]
• 4: [ 1, 12, 194, 199, 253 ]
• 5: [ 1, 12, 97, 99, 126 ]
• 6: [ 1, 12, 48, 50, 63 ]
• 7: [ 1, 12, 24, 25, 32 ]

Describe the solution you'd like

In Image3DModel.parse, an option to use a scale_factor of 2 along X and Y dims only, until min(X_size, Y_size) is less than original Z_size.

cc @EricMoerthVis @alexandra27i this is relevant for the 3D rendering, please feel free to comment

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