Add avaje-jsonb JsonOutput as performance option

[rbygrave]

When using JsonOutput, with json content smaller than the avaje-jsonb buffer, this can be written as fixed length content directly from the avaje-jsonb buffer to the http server outputStream without any additional buffering required.

Example using JsonbOutput:

ctx.status(200).contentType("application/json");
var result = HelloDto.fi();
jsonTypeHelloDto.toJson(result, JsonbOutput.of(ctx));