Add isc_sieve unit implementing SIEVE-LRU algorithm

Add isc_sieve unit implementing SIEVE-LRU algorithm

This is the core implementation of the SIEVE algorithm described in the
following paper:

  Zhang, Yazhuo, Juncheng Yang, Yao Yue, Ymir Vigfusson, and K V
  Rashmi. “SIEVE Is Simpler than LRU: An Efficient Turn-Key Eviction
  Algorithm for Web Caches,” n.d.. available online from
  https://junchengyang.com/publication/nsdi24-SIEVE.pdf