Python Redis Memory Connector should be able to take existing redis connection, not just connection string

[engt21]

Python redis memory connector should be able to take an existing redis connection. For example, some enterprises require/have other methodologies to connect to redis beyond the default connection string and those connections require additional parameters that cannot work with the default connection string.

Since connecting via the connection string also returns a redis.Redis object and sets it to the memory connector's database attribute, passing in an existing redis connector to set to that attribute should also work.

Have already discussed this briefly with a member of the team.

I will provide the implementation/fix that worked in my enterprise in PR.

[engt21]

Please let me know if/when/what next steps are before I can raise a PR. Thanks!