cubicweb-brainomics #3316345 Fix mix between filepath and results_file [deprecated]

We should only use on simple way to deal with all the different type of files (stored or not) in Brainomics

priorityimportant
typebug
done in0.9.0
load0.000
load left0.000
closed by#cefe672602e4 [schema, views] ExternalResources -> FileSet + FileEntry, closes #3316345
patch[schema, views] ExternalResources -> FileSet + FileEntry, closes #3316345 [applied]