Spatial subsets may raise out-of-memory error

[forman]

Describe the bug

Core function select_spatial_subset may raise an ArrayMemoryError for large spatial images, e.g. 129600 x 64800 pixels (ESA Land Cover CCI) although the dataset is chunked:

  File "D:\Projects\xcube\test\core\test_select.py", line 156, in test_xy_bbox_with_large_dataset
    ds_subset = select_spatial_subset(ds, xy_bbox=(0., 0., 5.0, 2.5))
  File "D:\Projects\xcube\xcube\core\select.py", line 99, in select_spatial_subset
    geo_coding = geo_coding if geo_coding is not None else GeoCoding.from_xy((x, y), xy_names=xy_names)
  File "D:\Projects\xcube\xcube\core\geocoding.py", line 172, in from_xy
    x, is_lon_normalized = _maybe_normalise_2d_lon(x)
  File "D:\Projects\xcube\xcube\core\geocoding.py", line 468, in _maybe_normalise_2d_lon
    if _is_crossing_antimeridian(lon_var):
  File "D:\Projects\xcube\xcube\core\geocoding.py", line 463, in _is_crossing_antimeridian
    return abs(lon_var.diff(dim=dim_x)).max() > 180.0 or \
  File "D:\Miniconda3\envs\xcube\lib\site-packages\xarray\core\dataarray.py", line 3107, in diff
    ds = self._to_temp_dataset().diff(n=n, dim=dim, label=label)
  File "D:\Miniconda3\envs\xcube\lib\site-packages\xarray\core\dataset.py", line 5489, in diff
    variables[name] = var.isel(**kwargs_end) - var.isel(**kwargs_start)
  File "D:\Miniconda3\envs\xcube\lib\site-packages\xarray\core\variable.py", line 2301, in func
    f(self_data, other_data)
numpy.core._exceptions._ArrayMemoryError: Unable to allocate 62.6 GiB for an array with shape (64800, 129599) and data type float64

Expected behavior

The spatial subset datasets should be created without errors and should also be chunked as the source.

Additional context

xcube 0.8.0

[forman]

Should be fixed in 0.,8.1