fix: clarified Redis connection errors and added Redis dependency to docker-compose files

[frolvanya]

• [x] Improve the error to make it less ambiguous, we need a clear message identifying it is related to connection to Redis

  Before:

  

  After:

  

• [x] Update the docker-compose.yml to ensure it is always in a working condition to docker-compose up from main

  To complete this, I've added redis dependency to postgres and rightsizing docker-compose files

• [x] Decide how to proceed with having Redis as a mandatory dependency and whether the rpc-server can work without it even with limited capabilities

  In any case we can merge these minor fixes now and later (@kobayurii @khorolets) will decide wether Redis is required or not

closes #274 closes #279

[frolvanya]

I would also like you to update the readme.md specify redis as an optional dependency and describe its use only when paired with near_state_indexer.

Should it be done in root README.md file or inside the rpc-server/README.md?

I've added some info to rpc-server/README.md, but I'm not sure if this is enough: https://github.com/near/read-rpc/blob/2a04ba3914128c8a0af01060123b249fda1383fb/rpc-server/README.md#redis-optional

[khorolets]

Should it be done in root README.md file or inside the rpc-server/README.md?

It's enough for now, we'll perform docs cleaning later.