Refactor functionalities and files

[DenisaCG]

Refactor s3contents.ts file and use an additional s3.ts file to store functions using the AWS SDK commands. Refactor these functions such that they can be reused and redundant code is eliminated (e.g. : use the same S3 function to save or create a new file, with different parameters).

Replace logic for path manipulation to use the official functions from the PathExt namespace.

Add descriptions to all S3 functions and smaller helping comments.