redis: Normalize RedisAddress factory as a single string

This PR normalize the RedisAddress to make it properly work.

I also think it makes the code more obvious.

• Only do the parsing inside factory (the constructor should not be called from outside)
• Properly distinguish port and sock
• The case localhost:2000 was not properly handled, falling down as unix://2000 url
• Convert port into int

(cherry picked from commit 2405c56a)