The rte_translator tour that test translation on the frontend could not
be started from the "[debug menu]" > "Start Tour" for two reasons:
- the start URL is not specified, so the test was started on current
backend page wich is wrong (in python the start url is "/")
- the backend original state (params after #) does not work with ?k=v
inside argument value, so `#return_url=/?debug=true`.
To solve this issue, we encode the return_url value and add a start url
when rte_translator is started manually.
opw-1998623
closes#33443
Signed-off-by: Nicolas Lempereur (nle) <nle@odoo.com>