[FIX] web_editor: enable to translate invisible blocks

Steps to reproduce the problem:
- Drop a popup snippet in a page.
- On another language, click on translate.
- Problem -> It is impossible to translate the popup.

To resolve this problem, the function `_updateInvisibleDOM` is called
even in translation mode. Thanks to this function, the invisible
snippets are now filled in the edit bar and the user has the opportunity
to display them or to hide them.

task-3098517
opw-3268592
opw-3283140

closes odoo/odoo#121219

X-original-commit: 04409af0
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>