Improve Error message for the countEquals predicate

[fabricereix]

Currently, the countEquals predicate produces error messages such as:

jsonpath "$.value1" countEquals 4
   actual:   string <hello>
   expected: count equals to <4>
   >>> types between actual and expected are not consistent

jsonpath "$.value2" countEquals 4
   actual: [object, object, object, object, object]
   expected: count equals to <4>

For the latest case where the type returned by the query is valid, namely a collection,
the error message could be improved as follows:

jsonpath "$.value2" countEquals 4
   actual: 5
   expected: 4