[DISCUSS] PIP-393: Improve performance of Negative Acknowledgement

[thetumbled]

Hi, Pulsar Community.
    I open a new PIP to fix several issues with negative ack feature. Most 
importantly, the memory occupation is less than 1% of the original 
implementation, which make it practical to work in the production enviroment.
    Some experiment data is listed in the PR, you can also verify the 
improvement with the test code i show.
    link: https://github.com/apache/pulsar/pull/23601

Thanks,
Wenzhi Feng(thetumbled)