Libervia-backend: Extract from old Libervia, add to new project structure

[OPNA2608]

Closes #553

[fricklerhandwerk]

Would it make sense to tuck under Libervia, or are the other components distinct applications as opposed to just components of the same application?

[OPNA2608]

#553 named "Libervia-backend" specifically, so I extracted only that part of the project here. If that was meant to include the desktop client in that, then I have no issue with migrating that into here as well, putting it all under "Libervia", and dropping /projects-old/Libervia.

[fricklerhandwerk]

Yes, please put everything together! :)

[OPNA2608]

Desktop client is now included in the new project structure:

• handled in module
• example for enabling the desktop client
• test for the desktop client (which has to import & extend the backend test, as it requires the libervia backend + all the same setup & environment to work in the VM)

I think this should be ready for review now.

[imincik]

Thanks ! Code looks good to me.

My only concern is that we lack some conventions or templates for file naming and code structure. Currently, all project metadata looks slightly different.

[fricklerhandwerk]

We'll get to stronger patterns once there's enough material to generalize over.