Add cancellation support for async add interface with pre-IO check

**FEATURE REQUEST**

Currently, the async add operation in Bookie (e.g., asyncAddEntry) lacks a mechanism to fast-fail if the request is cancelled before actual I/O (e.g., writeAndFlush). This can lead to unnecessary resource consumption (e.g., thread pool, queue, direct mem) for cancelled requests, especially in high-throughput scenarios where clients may cancel pending writes due to timeouts or application logic.