This commit introduces the Jackson2Tokenizer as a replacement for the
JsonObjectDecoder. The latter was dropped because of its complexity, and
hard dependency on Netty's ByteBuf.
The new Jackson2Tokenizer leverages the new non-blocking JSON parser,
using it to parse the incoming data buffers into TokenBuffers, each
token buffer representing one JSON object. As with JsonObjectDecoder,
it also supports streaming individual JSON array elements.
Issue: SPR-14528
31e0e53750