Slicing `net.imagej.Dataset` returns an `IntervalView` which does not support dimension metadata

[elevans]

Here is a minimal example using the test_timeseries.tif sample data from the PyImageJ repo.

import imagej

# initialize ImageJ
ij = imagej.init()

# load data
dataset = ij.io().open("doc/sample-data/test_timeseries.tif")
xarr = ij.py.from_java(dataset)

# slice data
xarr_slice = xarr[10, :, :, :]
dataset_slice = dataset[ :, :, :, 10]

The xarray slice maintains the associated image metadata:

>>>  xarr_slice.shape
>>>  (250, 250, 3)
>>>  xarr_slice.dims
>>>  ('row', 'col', 'ch')

But the dataset slice (net.imglib2.view.IntervalView) looses the metadata.

>>>  dataset_slice.shape
>>>  (250, 250, 3)
>>>  dataset_slice.dims
Traceback (most recent call last):
  File "<console>", line 1, in <module>
AttributeError: 'net.imglib2.view.IntervalView' object has no attribute 'dims'

We should and can do better here. Instead of IntervalView we should wrap slices as net.imagej.Datasets with the appropriate metadata.