Replace S3 with an open-source alternative.

[prshant70]

Let's make NotifyOne a cloud agnostic tool. And to achieve this, we first need to replace the AWS specific tools being used (s3, sqs) with other open-source counterparts.

This issue is about replacing S3 with and open-source counterpart.

If we don't find out a suitable open-source alternative to s3, we need to figure out what other options can be given to customers to store files (that are currently stored in s3). Customers will have choice between S3 and other file storage mechanisms to be chosen in the onboarding flow.

Let's debate it out..