NewtonsoftJsonOutputFormatter buffering improvements

[pranavkm]

Mvc's Newtonsoft.Json based serializer buffers contents to disk to avoid sync writes to the response stream. This was introduced in 3.0. We've received a few reports of people running in to issues with this. This issue tracks improvements to the buffering scheme:

• Allow configuring the size of the in-memory buffer
• Add benchmarks - Add benchmarks that test the scalability of large requests and large responses aspnet/Benchmarks#1498
• Optimize PagedByteBuffer so we page larger buffers (it's currently 1k)
• Optimize PagedByteBuffer so writing to disk is more efficient.

[pranavkm]

FYI @Tratcher \ @davidfowl \ @rynowak

[Tratcher]

• Fix the sync/async issues: Made changes to FileBufferWriteStream #21223

[shalinparmar]

When are we planning to release this as part of which version of Newtonsoft?