update french translation

update french translation

From the contribution author, Davy Defaud:

Please welcome a completed and reworked French translation for Proxmox
applications.

This translation takes care of:
- using the appropriate French words instead of Frenglish
- respecting the French orthotypographic rules:
  - no CamelCase for titles
  - use of guillemets (« ») instead of double right quotes
  - use true apostrophe (’) and hyphen (‐) instead of single right
    quote (') and dash (-)
  - use non-breaking space before colon (:) and closing guillemet
    (»), and after opening guillemet («)
  - use thin space before semi-colon (;), question and exclamation
    marks
- try to be gender neutral when a translation could depend on the
  gender (eg, “en cours d’exécution” for “running”, instead of
  “démarré” which could be “démarrée” depending of what is running
  [CT/VM])

Moreover, it fixes a lot of typos and misinterpretations.

Contributed-by: Davy Defaud <davy.defaud@free.fr>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>