Enable `fr` locale and fix bugs to support it

[devadvance]

Description

Enable fr locale and fix bugs to support it

Required checklist:

• [x] My code matches the existing code style of this project.
• One of these:
  • [x] This is a new localization for existing content.
  • [ ] This is new content that is localized for all the locales that this project currently supports.
  • [ ] I described above how I plan to localize this content immediately after merging these changes.
  • [ ] Localization is not applicable to this change.
• [x] I have tested my code and it successfully builds for GitHub Pages and validates as AMP.