[FIX] website: fix editor not starting after creating a website

Commit [1] introduced an automatic start of edit mode when
selecting a theme but didn't take into account wether the frontend lang
of the user was matching that of the website that is supposed to enter
in edit mode.

Commit [2] introduce a `website_edit` action but also didn't take into
account that the frontend lang might not be the source's lang.

Steps to reproduce:
- Create an empty database and install website
- Add an extra lang on website (e.g FR) and visit the website in that
lang
- Go in settings an create a new website, select a theme
- Redirect is with enable_editor but nothing happens

The editor isn't started if not in the source's lang.

This commit redirect the user to the default_lang of the website
so that editor can always be started. It also introduces a tour
to test out the flow.

[1]: https://github.com/odoo/odoo/commit/f474eac4543712ae5b1c7d614f9eff9367445107
[2]: https://github.com/odoo/odoo/commit/e0cc28dcee977c4aa0c6a7e4ff6c463ab12e55a2



task-2687416

closes odoo/odoo#83508

Signed-off-by: Romain Derie (rde) <rde@odoo.com>