Natively support Memory<byte>

[verdie-g]

There are many PRs open aiming to extend the API to allow low allocation produce but they all have some caveats:

• Binary Producer with Span<T> #1603 tries to support Span but given the constraints of that type, it means creating a whole new set of API.
• Improve serialization memory management #1725 suggests to use IBufferWriter instead, which unlike byte[] or Span, supports non-contiguous memory, kind of like Stream but it enables a lof of ways to reduce allocations. I don't think IBufferWriter is ideal here because in the end, a continuous memory buffer is expected for both the key and value. Also, the PR is introducing several breaking changes.
• Add a new type of Serializer for supporting zero allocation scenarios #2177 and Add ArraySegment<byte> as native supported type #2219 both propose to support ArraySegment which does not break the API and fixes the original problem. Though it would prevent the use of Memory<byte> which is the preferred type when dealing with contiguous memory when Span<byte> can't be used. This type is for example used in Stream.WriteAsync, Socket.SendAsync, and also in MemoryPool.Rent.

Instead of adding a third type of serializer (after ISerializer and IAsyncSerializer), this PR makes a special case for Memory<byte> (and ReadOnlyMemory<byte>) to by pass the serializers and directly use Message.Value or Message.Key.

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