Intent of add_to_empty

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
  - service/ 2 tests
    
    frontend/ 2 tests
    
    TestNamespaceHandlerCommonSuite/ 2 tests
    
    TestUpsertCustomSearchAttributesAliases/ 2 tests
    
    go.temporal.io/server/service/frontend/TestNamespaceHandlerCommonSuite/TestUpsertCustomSearchAttributesAliases/add_to_empty Introduced here
    
    go.temporal.io/server/service/frontend/TestNamespaceHandlerCommonSuite/TestUpsertCustomSearchAttributesAliases/add_to_existing Inherited add_to_existing