Use ROS<byte> instead of byte[] where it makes sense on S.S.C.Cose (#66741)

Use ROS<byte> instead of byte[] where it makes sense on S.S.C.Cose (#66741)

* Use ROS<byte> instead of byte[] on S.S.C.Cose

* Add TrySign and improve Sign implementation to use less byte[]

* Add TrySign tests

* Address using scope feedback

* Address src feedback

* Refactor tests to avoid duplicated ones

* Remove invalid asserts in Crypto code

* Fix 'new()' without the type on the left-hand side

* Fix ThreadStatic issues in tests

* * Don't use ArrayPool in SignCore
* Add comment describing reusability of encoded protected headers
* Cache toBeSigned

* Don't cache toBeSigned for detached content

* Address nits in tests