Add rivertest.WorkContext for use testing JobArgs.Work implementations
#831
| Job | Run time |
|---|---|
| 2m 35s | |
| 27s | |
| 2m 50s | |
| 51s | |
| 3s | |
| 3m 1s | |
| 2m 17s | |
| 1m 37s | |
| 1m 59s | |
| 1m 48s | |
| 17m 28s |