Intent of TestMigrateToWorkflow_Sentinel, TestSentinelHandler_MigrateToWorkflow

All 2 exact tests in this concept. Every test is marked by where it enters the hierarchy.

go.temporal.io/ 2 tests
- server/ 2 tests
  - chasm/ 2 tests
    
    lib/ 2 tests
    
    scheduler/ 2 tests
    
    go.temporal.io/server/chasm/lib/scheduler/TestMigrateToWorkflow_Sentinel Introduced here
    
    go.temporal.io/server/chasm/lib/scheduler/TestSentinelHandler_MigrateToWorkflow Introduced here