chore: adding mocked S3 bucket for local filestore

[sarthakpranesh]

Wrote a very basic mocking for S3 bucket operations to local file system using fs. When running the docker container we can pass in a persist volume and have it map internally to localFileStore so that our data remains persisted even if docker containers are destroyed and rebuild.

Links to this issue - mydraft-cc/ui#234

Routes checked

• GET /:tokenRead
• POST /
• PUT /:tokenRead/:tokenWrite
• GET /health
• Web Socket /collaboration [not sure how to check this]