Bug: QPU.execution_options not used for QPU.retrieve_results

[kalzoo]

QPU allows execution_options to be set on both the class instance itself (self.execution_options) or on the .execute request(execution_options arg). It follows the right precedence order when calling submit, but does not consider self.execution_options in the construction of QPUExecuteResponse (here).

One effect of this: if get_qc() is invoked with an endpoint_id, that endpoint is not used for results retrieval, and pyQuil tries to use the default instead (gateway). If no such gateway exists, then results retrieval fails.

This can be quickly fixed, and should be covered with a new test.