DictionaryKeyPolicy not applied to keys that contain non primitive ty… (dotnet/corefx#41691)
* DictionaryKeyPolicy not applied to keys that contain non primitive types dotnet/corefx#41176
https://github.com/dotnet/corefx/issues/41176#event-
2697607085
* dotnet/corefx#41176: DictionaryKeyPolicy not applied to keys that contain non primitive types
https://github.com/dotnet/corefx/issues/41176
* add unit tests
https://github.com/dotnet/corefx/pull/41691
* Remove check for JsonExtensionDataAttribute to avoid reflection.
Commit migrated from https://github.com/dotnet/corefx/commit/
d9dd0dac4285368002740333d6772d4db79d82c1