chore: add cspell fr language

.vscode/extensions.json

+{
+  "recommendations": ["streetsidesoftware.code-spell-checker"]
+}

.vscode/settings.json

@@ -40,6 +40,7 @@
     "connectionId": "sonarqube-forge-grandlyon",
     "projectKey": "web-et-numerique-llle-project-backoffice-client"
   },
+  "cSpell.language": "fr,en",
   "cSpell.words": [
     "backoffice",
     "draftjs",