general: legacy directory pre-creation

* Ensures legacy directories are pre-created upon legacy extension
  `setup_app()` call.  (closes #1789)

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>
Reviewed-by: Yoan Blanc <yoan.blanc@cern.ch>
Reviewed-by: Jiri Kuncar <jiri.kuncar@cern.ch>
assets: filters behavior fix

* Fixes the filters behaviour when no variables are set in the config.

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
Reported-by: Georgios Kokosioulis <georgios.kokosioulis@cern.ch>