Add redis cluter mode for pubsub

[Taction]

Description

Add redis cluter mode for pubsub, change *redis.Client to a redis.UniversalClient interface which can be a Client or ClusterClient.Add a redisType metadata to define redis type as node or cluster.
There are two differences between redis cluster and node.

1. redis cluster's addr option is a string array, which is a string in node. Alough cluster client can find all redis cluster nodes by one redis node, but in case the node is breakdown that the cluster can get cluster nodes info by other nodes. It is better to define addr in cluster mode can include more nodes adderss separated by comma.
2. redis cluster can not define db option for it only use default db0.

Issue reference

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation / Created issue in the https://github.com/dapr/docs/ repo: [CONTENT] add redis cluster mode for PubSub component docs#1431

[Taction]

I've finished modify related docs and create an issue in the doc project.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@744e5be). Click here to learn what that means.
The diff coverage is 4.16%.

@@            Coverage Diff            @@
##             master     #823   +/-   ##
=========================================
  Coverage          ?   34.63%           
=========================================
  Files             ?      102           
  Lines             ?     9414           
  Branches          ?        0           
=========================================
  Hits              ?     3261           
  Misses            ?     5844           
  Partials          ?      309           

Impacted Files	Coverage Δ
pubsub/redis/redis.go	27.00% <4.16%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 744e5be...49d1438. Read the comment docs.