Particularly to confirm the validity of the migration from LAMA to Dask in #182, we should add a new test method to explicitly test the Data.equals method as it does not seem to be unit tested yet, despite the other tests relying on it for many test assertions.

This would be a test akin to test_Field_equals and similar test methods as existing for CellMethod and CoordinateReference currently, so the name test_Data_equals would be consistent with those.