WHAT
Review the work already spiked for Redis Creation.

Implement any missing logic for Creation of a Redis in GCP

We should aim to follow a similar pattern where the CreateConfig is mapped from the create strategy to a CreateReplicationGroupInput param in the GCP package. See here for example -> https://github.com/integr8ly/cloud-resource-operator/blob/master/pkg/providers/aws/provider_redis.go#L838-L897

Implement unit tests for the new functions added

HOW
Review changes in working branch linked in the epic brief for functionality around creating a redis in GCP.

TESTS
Unit tests added

DONE
Redis Creation functionality in GCP that matches AWS implementation