i18n: localize the editor toolbar in all 23 locales

The rich-text editor was the last hardcoded-English surface in the
composer: 21 tooltip titles, the eight table-menu entries, the "Remove
color" entry and the table size picker's "Pick size" label were plain
strings while every other menu in the app is localized.

All of them now come from a new email_composer.toolbar namespace,
translated into all 23 locales using each platform's established
editor terminology (Word/Docs conventions - de "Formatierung löschen",
ar "مسح التنسيق", ja "書式をクリア", ...). The link prompt stays "URL",
which is the same term in every language.

Tooltips and self-sizing dropdowns have no width constraints, so longer
translations are safe everywhere.

locales/he/common.json

@@ -651,6 +651,38 @@
     "recipient_name_placeholder": "שם תצוגה",
     "autocomplete_search_server": "חיפוש בשרת",
     "autocomplete_searching": "מחפש...",
+    "toolbar": {
+      "bold": "מודגש",
+      "italic": "נטוי",
+      "underline": "קו תחתון",
+      "strikethrough": "קו חוצה",
+      "text_color": "צבע טקסט",
+      "remove_color": "הסרת צבע",
+      "heading_1": "כותרת 1",
+      "heading_2": "כותרת 2",
+      "bullet_list": "רשימת תבליטים",
+      "ordered_list": "רשימה ממוספרת",
+      "quote": "ציטוט",
+      "code_block": "בלוק קוד",
+      "align_left": "יישור לשמאל",
+      "align_center": "מרכוז",
+      "align_right": "יישור לימין",
+      "text_direction": "כיוון טקסט (RTL/LTR)",
+      "link": "קישור",
+      "table": "טבלה",
+      "clear_formatting": "ניקוי עיצוב",
+      "undo": "ביטול",
+      "redo": "ביצוע מחדש",
+      "add_row_above": "הוספת שורה מעל",
+      "add_row_below": "הוספת שורה מתחת",
+      "add_column_before": "הוספת עמודה לפני",
+      "add_column_after": "הוספת עמודה אחרי",
+      "delete_row": "מחיקת שורה",
+      "delete_column": "מחיקת עמודה",
+      "toggle_header_row": "החלפת שורת כותרת",
+      "delete_table": "מחיקת טבלה",
+      "pick_size": "בחירת גודל"
+    },
     "send_filing_warning": "נשלח - אך הניקוי שלאחר השליחה נכשל, ייתכן שתישאר טיוטה ישנה."
   },
   "confirm_dialog": {