Setup Redis 6 with TLS on Ubuntu 18.04

https://gist.github.com/fritsstegmann/316cc0d458604d08bf1b9ac517c1428f

References
https://redis.io/download
https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-redis-on-ubuntu-16-04
https://gist.github.com/fntlnz/cf14feb5a46b2eda428e000157447309
https://redis.io/topics/encryption
https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-redis-on-ubuntu-18-04