iohub appending does not change or raise warning regarding datatype

[edyoshikun]

The iohub Position.append_channel() function works great when the array to have a channel appended to shares the same dtype. In this case, we have some datasets stored as dtype=np.uint16 and when attempting to append a np.float32 dtype array, this proceeds without a warning.

The appropriate behaviour should be to raise a warning. In the case of having to change the whole dtype, I think it is probably easier to create a new zarr store, copy in the data, and then delete the old zarr store.

[ziw-liu]

iohub.ngff.Position.append_channel only takes in the new channel name and a flag to resize arrays. It does not take any data as input. Where do you think the warning should be triggered?