Provide standard methods to read files independently from the provider

[javiertoledo]

For instance, if you're storing a CSV file, no matter if your file is stored on a Blob storage (Azure) or a local file (Local provider), it would be convenient to have a function provided by the rocket that returns a read stream that can be connected to libraries like csv-parser.

In this way, we also abstract the access to the file in addition to the file upload.