Add another test using the dataset shape

[imsdu]

Before:

[info] NeuroMorphologySampleSpec:
[info] Creating a morphology
[info] - should succeed provisionning the mandatory schemas (5 seconds, 372 milliseconds)
[info] - should succeed creating the neuronmorphology-entity without a schema (154 milliseconds)
[info] - should succeed creating the neuronmorphology-entity with a schema (3 seconds, 47 milliseconds)
[info] - should succeed updating the neuronmorphology-entity with a schema (2 seconds, 940 milliseconds)
[info] - should succeed creating the neuronmorphology-dataset without a schema (82 milliseconds)
[info] - should succeed creating the neuronmorphology-dataset with a schema (2 seconds, 194 milliseconds)
[info] - should succeed updating the neuronmorphology-dataset with a schema (2 seconds, 176 milliseconds)

After:

[info] NeuroMorphologySampleSpec:
[info] Creating a morphology
[info] - should succeed provisionning the mandatory schemas (2 seconds, 917 milliseconds)
[info] - should succeed creating the neuronmorphology-entity without a schema (97 milliseconds)
[info] - should succeed creating the neuronmorphology-entity with a schema (2 seconds, 64 milliseconds)
[info] - should succeed updating the neuronmorphology-entity with a schema (2 seconds, 18 milliseconds)
[info] - should succeed creating the neuronmorphology-dataset without a schema (58 milliseconds)
[info] - should succeed creating the neuronmorphology-dataset with a schema (1 second, 554 milliseconds)
[info] - should succeed updating the neuronmorphology-dataset with a schema (1 second, 540 milliseconds)