Intent of NullMaxIntField, NullMinIntField, +4

All 6 exact tests in this concept. Every test is marked by where it enters the hierarchy.

go.temporal.io/ 6 tests
- server/ 6 tests
  - common/ 6 tests
    
    persistence/ 6 tests
    
    visibility/ 6 tests
    
    store/ 6 tests
    
    elasticsearch/ 6 tests
    
    TestESVisibilitySuite/ 6 tests
    
    Test_parsePageTokenValue/ 6 tests
    
    go.temporal.io/server/common/persistence/visibility/store/elasticsearch/TestESVisibilitySuite/Test_parsePageTokenValue/NullMaxBoolField Introduced here
    
    go.temporal.io/server/common/persistence/visibility/store/elasticsearch/TestESVisibilitySuite/Test_parsePageTokenValue/NullMaxDatetimeField Introduced here
    
    go.temporal.io/server/common/persistence/visibility/store/elasticsearch/TestESVisibilitySuite/Test_parsePageTokenValue/NullMaxIntField Introduced here
    
    go.temporal.io/server/common/persistence/visibility/store/elasticsearch/TestESVisibilitySuite/Test_parsePageTokenValue/NullMinBoolField Introduced here
    
    go.temporal.io/server/common/persistence/visibility/store/elasticsearch/TestESVisibilitySuite/Test_parsePageTokenValue/NullMinDatetimeField Introduced here
    
    go.temporal.io/server/common/persistence/visibility/store/elasticsearch/TestESVisibilitySuite/Test_parsePageTokenValue/NullMinIntField Introduced here