Open the composer full screen, as a setting (#401) (#404)

Settings > General > Composing has a new switch, "Open the composer full
screen". With it on, every new composer, whether a new message, reply,
forward or reopened draft, starts maximized. Restore still shrinks it to
a window. A draft put back after an undone or failed send keeps the size
it had. It's off by default, and on a phone, where the composer already
fills the screen, it changes nothing.

One new string, translated in all nine catalogs. The count falling back
to English stays at 16 in every language.

Fixes #401

web/src/locales/fr.ts

@@ -755,6 +755,7 @@ export const catalog: Catalog = {
     "Attachment reminder": "Rappel de pièce jointe",
     "Warn when the message mentions an attachment but none is attached.": "Avertir lorsque le message mentionne une pièce jointe alors qu'aucune n'est jointe.",
     "Spell check while typing": "Vérification orthographique pendant la saisie",
+    "Open the composer full screen": "Rédiger les messages en plein écran",
     "Confirm before deleting": "Confirmer avant de supprimer",
     "Show message snippets": "Afficher un aperçu des messages",
     "Preview the first line of each message in the list.": "Afficher la première ligne de chaque message dans la liste.",