[FIX] web_editor: use styling commands on shortcut too

When pressing the italic or underline buttons, we pass through a command
in the editor. Their corresponding keyboard shortcuts however were not
intercepted by the editor and were therefore triggering the default
browser behavior. As a result we had different behaviors when using the
buttons and the shortcuts.

X-original-commit: 2e3c3b3a15fa6ff4fa209fc7dbac10864f8898a2
Part-of: odoo/odoo#86930