[Bug]: Redisinsight should change `theme` key of local storage

[Atsushi Koge]

When Redisinsight runs subpath mode and share origin with multiple applications and uses same local storage key, it became not to work.

As my experience, external application uses theme key in local storage and parses its value as JSON, but Redisinsight saves just a string value to theme as below.

https://github.com/RedisInsight/RedisInsight/blob/main/redisinsight/ui/src/services/theme.ts#L38

So I think this should change key name more specific like "redisinsight-theme" because Redisinsight can run by subpath mode.