feat: support redis sentinel mode #2381

[kayoch1n]

Issue #2381

This PR introduces Redis Sentinel support in go-zero by leveraging redis.NewFailoverClient from go-redis/v9, enabling high availability without requiring Redis Cluster.

Key changes:

• Added new SentinelType constant to distinguish Sentinel mode
• Updated client creation logic to use NewFailoverClient when Type: SentinelType
• Configuration now accepts comma-separated Sentinel addresses in Host and requires MasterName
• Added unit tests for Sentinel client initialization

Example usage:

	c := redis.MustNewRedis(redis.RedisConf{
		Type: redis.SentinelType,
		Host: strings.Join([]string{
			"10.244.2.24:26379", // the addresses of sentinel instances
			"10.244.1.15:26379",
			"10.244.2.26:26379",
		}, ","),
		MasterName: "mymaster",
	})

The returned *redis.Client remains fully compatible with the existing RedisNode interface.

This is a recreated PR of #5438