Fail if ROWID shape and chunks don't match associated dataset arrays

[sjperkins]

Closes #238

• [x] Tests added / passed

  $ py.test -v -s daskms/tests

  If the pep8 tests fail, the quickest way to correct this is to run autopep8 and then flake8 and pycodestyle to fix the remaining issues.

  $ pip install -U autopep8 flake8 pycodestyle
  $ autopep8 -r -i daskms
  $ flake8 daskms
  $ pycodestyle daskms

• [x] Fully documented, including HISTORY.rst for all changes and one of the docs/*-api.rst files for new API

  To build the docs locally:

  pip install -r requirements.readthedocs.txt
  cd docs
  READTHEDOCS=True make html

[sjperkins]

Running this PR on the reproducer in #239 now results in the following error:

Traceback (most recent call last):
  File "tmp/repro.py", line 26, in <module>
    writes = xds_to_table(xds, ms_name, columns=["BROKEN_DATA"])
  File "/home/simon/code/dask-ms/daskms/dask_ms.py", line 96, in xds_to_table
    out_ds = write_datasets(table_name, xds, columns,
  File "/home/simon/code/dask-ms/daskms/writes.py", line 725, in write_datasets
    write_datasets = _write_datasets(table, tp, datasets, columns,
  File "/home/simon/code/dask-ms/daskms/writes.py", line 629, in _write_datasets
    raise ValueError(f"ROWID shape and chunking does not "
ValueError: ROWID shape and chunking does not match that of BROKEN_DATA

[sjperkins]

Thanks for the review!