Intent of terminate_started_activity, terminate_scheduled_activity, +1

All 3 exact tests in this concept. Every test is marked by where it enters the hierarchy.

go.temporal.io/ 3 tests
- server/ 3 tests
  - chasm/ 3 tests
    
    lib/ 3 tests
    
    activity/ 3 tests
    
    TestActivityTerminate/ 3 tests
    
    go.temporal.io/server/chasm/lib/activity/TestActivityTerminate/terminate_cancel-requested_activity Introduced here
    
    go.temporal.io/server/chasm/lib/activity/TestActivityTerminate/terminate_scheduled_activity Introduced here
    
    go.temporal.io/server/chasm/lib/activity/TestActivityTerminate/terminate_started_activity Introduced here