James Lai

Add support for cluster client in go-redis client tracing library.

2

The official go-redis client exposes a [ClusterClient](https://pkg.go.dev/github.com/redis/go-redis/v9#ClusterClient) which is exposed via [NewClusterClient](https://pkg.go.dev/github.com/redis/go-redis/v9#NewClusterClient). However, this tracing library only exposes the UniversalClient: https://github.com/DataDog/dd-trace-go/blob/076462ab8f4e82da892f10145568973d7c0eb638/contrib/redis/go-redis.v9/redis.go#L44 This is problematic, as the implementation of the UniversalClient...