Add a way of setting .data

[Cadair]

Describe the feature

I frequently have the case when working with DKIST data that I want to in-place compute the dask array, i.e. this:

spatial_avg = visp.rebin((-1, 1, -1), ).squeeze()
spatial_avg._data = spatial_avg.data.compute()

it would be nice if I didn't have to use ._data.

Proposed solution

Add a setter for .data which validates the new array is the same shape as the old array.