Add Redis cache support

[georgi-l95]

Problem

We currently have methods that need to share their cache between different relay instances. Otherwise they might not operate properly.

Solution

Add Redis support in the relay and refactor cacheClient to support using either lru or redis, depending on method.

Tasks

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1. Add design documentation for distributed cache #1641
   P1 documentation enhancement +3
   
2. Refactor cacheClient to support distributed cache #1665
   P1 enhancement +2
   
3. Add Redis to Local-Node hedera-local-node#385
   +0
   
4. Refactor eth_filter and eth_subscribe to use shared cache #1650
   enhancement +1
   
5. Add metrics to RedisCache #1686
   enhancement +1
   
6. Add acceptance test for redis cache #1687
   enhancement +1
   
7. Add a redis instance to relay docker-compose #1869
   good first issue hacktoberfest internal +3
   
8. Add redis to relay helm chart as a dependency #1870
   good first issue hacktoberfest +2

Alternatives

No response

[Nana-EC]

@georgi-l95 can we close this or are the 2 remaining items still open?

[georgi-l95]

@Nana-EC Closing, as I think those are not needed. We can reopen, if needed.