System.Text.Json: Add IAsyncEnumerable support (#50778)

System.Text.Json: Add IAsyncEnumerable support (#50778)

* implement IAsyncEnumerable JsonConverter

* Prototype of IAsyncEnumerable deserialize with Stream

* Use a Queue + test buffersizes

* Avoid 1 item lag

* Add support for Serialize

* Misc cleanup on test

* extend DeserializeAsyncEnumerable test coverage

also removes SerializeAsyncEnumerable components

* Update src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Collection/IAsyncEnumerableConverterFactory.cs

Co-authored-by: Stephen Toub <stoub@microsoft.com>
* address feedback

* tweak test buffer values

* Update src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Collection/IAsyncEnumerableOfTConverter.cs

Co-authored-by: Stephen Toub <stoub@microsoft.com>
* Update src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Collection/IAsyncEnumerableOfTConverter.cs

Co-authored-by: Stephen Toub <stoub@microsoft.com>
* address feedback

* increase delayInterval in serialization tests

* address feedback

* address feedback

* add test on exceptional IAsyncDisposable disposal

* address feedback

* Update src/libraries/System.Text.Json/src/System/Text/Json/Serialization/ReadAsyncState.cs

Co-authored-by: Layomi Akinrinade <layomia@gmail.com>
* Update src/libraries/System.Text.Json/src/System/Text/Json/Serialization/WriteStack.cs

Co-authored-by: Layomi Akinrinade <layomia@gmail.com>
* fix build and remove dead code

* address feedback

* Revert unneeded JsonClassInfo.ElementType workaround

* remove state allocation on async deserialization methods

* remove tooling artifacts

* address feedback

* reset AsyncEnumeratorIsPendingCompletion field

Co-authored-by: Steve Harter <steveharter@users.noreply.github.com>
Co-authored-by: Stephen Toub <stoub@microsoft.com>
Co-authored-by: Layomi Akinrinade <layomia@gmail.com>