Add a new prerogative: "Developed by a French company"

Currently, there is no easy way to know when a piece of Free Software is developed by a French company.

The proposal is to add a new prerogative "Developed by a French company" when relevant, with a new search filter "Is developed by a French company".

"Developed" is to be understood as "the governance for the source code of the referenced repository is defined by": of course we acknowledge that Free Software projects can be highly collaborative, but this doesn't make it impossible to know who owns the code and/or who controls the governance of the project delivering the product.

IMHO, we don't need to advertise the company (just as we don't advertise the public administration in the case of Free Software developed by public administrations), because it can be inferred from the repository.

WDYT?

No files, tests, or entry points are named. First clarify how a French company is identified and where the new prerogative is represented, then trace the existing prerogative and search-filter implementations. Done means the catalog exposes the new prerogative and the “Is developed by a French company” filter with agreed governance semantics.

Written by the indexing model from the issue text.