Enhancement: Multiple ADNCA files uploading

[Gero1999]

Description

In some cases more than 1 study wants to be uploaded at the same time by the user in order to perform certain comparison operations.

Definition of Done

The requirements for the feature to be complete:

• Allow multiple files as input of the application and bind (e.g, rbind) them in one file
• Presumably the app will keep all funcionalities. Perhaps it is needed some checking that all combined files present the same column format (so the mapping keeps working). However, this checking will depend on the implementation.