Enhancement bulk upload

The current bulk upload only parallelizes the upload of a single file and handles the files within the folder sequentially.

What we want to do is also parallelize the handling of files in the folder.

As an initial step, we will leave the already improved single-file upload function as it is.

We will then focus on parallelizing the upload of multiple files simultaneously.

For simplicity, as a first assumption, we will try to handle many files, but of small size.

Add some preliminary checks

• If the user is already logged in otherwise stop
• Manage row and yes option
• Enhancement progress bar

@mpuccini