TypeConstraint checks if a value is really a numeric array or it's an object

[Alex-PK]

As JSON objects are represented as PHP arrays once decoded, the type check didn't work when importing json or yaml files.
I improved the check for both arrays and objects.

[Alex-PK]

I added a check for empty arrays for both array and object check.
Most tests pass, but 2 from schema-v3 don't, as they test empty arrays and objects which, in PHP, are equivalent.

The alternative would be to go back to check only for is_object() and is_array(), but this would force to use stdClass everywhere a json object is needed.

I am open to suggestions as to how to manage this.

[bighappyface]

@Alex-PK any movement on this regarding testing?