"Layer number" in Subject's Multiplex layout

[bzufiriaki]

"Layer Number" is in the layout when opening subjects in multiplex pipelines.

We need to check if we really want this information in the layout. If we want this information, then we should block the cell so that users cannot change the number of layers (they will get an error)

Error if you try to change the value in "Layer Number":

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After some discussion we conclude that we do not need the Layer Number in the Layout. However, Layer Number is used when calculating FUN_MP so it will be kept in props. On the other hand, we need to modify the Layer Labels so that the number of Layer Labels is always equal to the number of layers. In order to do so, we need to modify the Layer Labels in postset in the Subjects MP