allow to configure s3 subpath (bucket prefix configuration

Is your feature request related to a problem? Please describe. Currently a full S3 bucket is required for Loki - however, in some situations a bucket may need to be shared with other apps (one example would be aws lightsail where there's

AWS quickstart

Alexa Rest API Used to Update TigerGraph Cloud Vertex Data

AS2 Gateway - AWS S3 Integration

S3 via Lambda InsightOps Documentation

Storage configuration

web services - Unable to apply lifecycle policy on s3 bucket when prefix is nested - Stack Overflow

Configure Cloud Storage: /Documentation

web services - Python way of setting a s3 subdirectory path and deleting it using boto - Stack Overflow

Backing up Configs and Archived Logs on S3 Bucket

Configure lifecycle management for logs on AWS

Refreshing Directory Tables Automatically for S3