Add "jobSearchMode" as a condition to "/kylin/api/jobs" API

In kylin 2.3, the "/kylin/jobs" API will return both cubing job and checkpoint job together, this changed the API's behavior as there isn't checkpoint job before. We should keep the api only return cubing jobs to be compitable as before, and extend the API to add another condition 'jobSearchMode' to determine which kind of job should be returned.