chore(tocco-client): fix relative backend url
chore(tocco-client): fix relative backend url

- 'http://8080' did not proper work as relative backend dev url. 'Fetch' was not able to parse such urls.
- JSON.stringify will not work with the new fix because the expression (window.location.hostname) would be evaluated during compile time

tocco/tocco-client,tocco/tocco-client,tocco/tocco-client