Add replication capabilities

[axblueblader]

Features:

1. • [ ] Slave registration
2. • [ ] Transfer snapshot file for slave to load current state
3. • [ ] Relay committed operations to slave
4. • [ ] Master slave connection checking
5. • [ ] Partial synchronization for temporary failures with help of write-ahead log
6. • [ ] Slave promotion
7. • [ ] Dedicated protocol for internal communication

Ideas based on Redis replication feature:

• Redis Replication official documentation
• Redis Replication deep dive video
• The most in depth explanation article
• Blog post about PSYNC from Redis founder
• Blog post about replication from Redis founder

[axblueblader]

#19 implemented basic prototype for [1], [2] ,[3]

[axblueblader]

#21 added [4] capability on master side

[axblueblader]

Additional references: https://javamana.com/2021/02/20210212015506083E.html

https://titanwolf.org/Network/Articles/Article?AID=0e2abeac-c210-4c7f-a618-4b8f45b221be

https://www.fatalerrors.org/a/redis-the-mystery-of-replication.html