Xray can migrate all test executions from Zephyr ad-hoc cycles

Background:
Currently the Zephyr to Xray migration is designed to migrate only the most recent test execution from the Ad Hoc cycle for each test case. This results in important data not being migrated into Xray.
 
Suggestion:
When migrating, allow users to choose between migrating the most recent test execution and transforming the test cycle so all test executions are represented in Xray