stOTTR parsing tests
Create a setup that allows for testing stOTTR parsing -- located in the stOTTR module (and not in CLI module, see #380 (closed)), that allows for testing correctness (and robustness) of stOTTR parsing. The setup should make it easy to add negative (testing for identifying errors) and positive test (parsing correct stOTTR syntax). For the negative tests it should be possible to check that the error is correctly found (perhaps by checking error messages returned). For positive tests one could check the results by investigating that the parsed internal model is as expected, e.g.,
a:Template[ottr:IRI ?x] :: {}
should give a template with one parameter with the type ottr:IRI and a body with 0 instances.