Lab 1: Exactly-Once

We are not allowed to share codes online.

For more details, Pls refer to NUS CS5223 Lab's Repo: https://github.com/nus-sys/cs5223-labs/tree/main/labs/lab1-clientserver

1. kv store, support put, get, and swap
2. at-most-once app
3. retries logic on Client side
4. seq-id maintaining