[Feature] Support for redis sentinel connection for cache

[DivPro]

Is your feature request related to a problem? Please describe.
I have a HA Redis cluster supported by sentinels. But the current config only supports single and cluster Redis modes.
chproxy already uses UniversalClient from go-redis, but doesn't have the required sentinel config variables here: https://github.com/ContentSquare/chproxy/blob/master/clients/redis.go

Describe the solution you'd like

1. Add optional variables required for sentinel mode: MasterName (required for sentinel) and optional SentinelUsername + SentinelPassword.
2. Fix go code / docs / examples / tests.
3. Make the necessary PR.

Describe alternatives you've considered
Using specialized proxies to automatically switch the dynamic address to the Redis master (like https://github.com/RedisLabs/sentinel_tunnel)