[IMP] website: open the theme_install_kanban_action in the webclient

Before this commit, the switchTheme option was redirecting the window to
the theme_install_kanban_action url.

After [1] was merged, the editor is instantiated inside the webclient
and the action can now be opened directly from there, without a reload.

For that, the request_save event data can include an 'action' parameter,
which the WysiwygAdapter will use after leaving debug mode to trigger
the action with the action service.

[1]: https://github.com/odoo/odoo/commit/31cc10b91dc7762e23b4bde9b945be0c4ce3fe3b



task-2687506

closes odoo/odoo#81485

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>