* Propagate CancellationToken request cancellation to remote endpoint
* Refactor existing tests to have a shared base class
* Add cancellation tests
---------
Co-authored-by: Stephen Toub <stoub@microsoft.com>
* Allow user-defined JsonSerializerOptions for user-defined and inputs and hardcode everything else to the source generator.
* Add validation for user-defined JsonSerializerOptions.
* Remove out of date comment.
* Address feedback and add tests