Mock LibreOffice test backend

[xtiannyeto]

Mock LibreOffice on backend test

✍ Prerequisites:

🤸‍♂️Need

🧿Fontend needs:

🧿Backend needs:

'execute AEM export return a MissionAEMExportEntity when mission and action exist' failed when we don't have libreOffice install.
Mock LibreOffice part, as the goal is not to test libreOffice.

📦Design

Design specs:

🧩Test

🔭 Estimation = ?? jours****