fix(client): Do not fail on startup if cookies or access to dom.storage is disabled.

* Work with the author of crosstab to ensure it works as expected with cookies and localStorage disabled.
* Ensure the /cookies_disabled page renders if the user reloads it while cookies are disabled.

fixes #1848
Merge pull request #1866 from mozilla/issue-1848-localstorage-disabled

fix(client): Do not fail on startup if cookies or access to dom.storage is disabled.