french-specific date locale

[mchangrh]

• append h to times

• replace - with à 10 - 12 becomes 10h à 12h

  dates - prepend le mecredi - 07 avril becomes mecredi - le 07 avril

[mchangrh]

related: https://moment.github.io/luxon/docs/manual/formatting.html#tolocalestring--strings-for-humans-

[mchangrh]

Luxon and Intl seem to omit h/heure and le in their date strings. While this would be nice to have and would be much more proper, It is far out of scope for Niles, adding locale & country-specific language is not the job of Niles but of Intl maintainers