Improve paper file API

[tdurieux]

The current API has two API to retrieves the file list of a paper (files compatible with synchronization and other). I think, it is better to let the client decides which files can be synchronized and thus have only one API to retrieve all files.

Other shortcomings

When a paper has a lot of file, generally the user went create folder to sort his file. The current version of BlueLaTeX doesn't support folder.

Currently, it's not possible to rename a file.

Summary

• [ ] Create an API to retrieve all files
• [ ] Add support of folders
• [ ] Create an API to rename a file