Add Skip and TrySkip APIs to Utf8JsonReader with tests. (dotnet/corefx#37793)
* Add Skip and TrySkip APIs to Utf8JsonReader with tests.
* Auto-generate the ref assembly.
* Remove new lines and update bytes consumed to avoid adjusting OS specific offsets.
* Add IsFinalBlock public property.
* Break up the skip/try skip method into helpers.
* Add more direct tests and update impl to avoid unnecessary struct copy.
Commit migrated from https://github.com/dotnet/corefx/commit/
2f2aca43ef9d24c794255c3ef5d0238dc479652b