Create proper export template for the French state

[virgile-dev]

Feature Request

Is your feature request related to a problem or unsupported use case? Please describe.
Right now the French State Template only display the Marianne logo at the top. In reality templates are a bit more advanced, in order for agents to avoid having to do copy paste from docs to a word or odt document we can try and get closer to what they are using right now

Describe the solution you'd like
This should not be inside the generic repo as every instance will have their own templates.
I'd like to start experimenting with real templates.
Here are 3 I got my hand on, we need to figure out what we keep in the template and what info we let the user enter himself.
ModèlePM_WORD_DINUM_Courrier.docx
MPME-Lettre.docx
MPME-Note.docx
@rl-83 I think it'd be nice for you to have a look at these

Describe alternatives you've considered
Let the users use the editor + multi column to create their own templates and add a duplicate or use as template feature

Discovery, Documentation, Adoption, Migration Strategy
Docs started as a project to print markdown pads made in hedge doc.
We could even use a grist integration to fill in some of the info (publipostage)

Do you want to work on it through a Pull Request?