Avoid file creation with file already used

[Sergio-Muriel]

When making a request to POST /ds-api/data/
with:
{
docType: 'folder'
path: '',
name: 'my_folder'
}

It allows me to create a folder with the same name of a folder in my root directory (it shouldn't be allowed).

[poupotte]

Actually, it should be application which checks if folder is duplicated or not.

[nono]

Currently, the data-system lets the applications write whatever they want if they have the permission for that (related to the docType). And each app have to check to not create duplicate files or folders, or that a file is in an existing folder.

It's tedious, so I think on the long term, we should propose a Files API (probably as a part of the data-system) to implement the manipulation of files with high-level methods. This bug will probably stay in the idea box for some time, to let us mature this idea.