Better inform user when session is lost

When connectivity is lost, no warning is provided to alert the user that their configuration save hasn't been successful.

Expected:

• User should be informed and as much as possible be able to keep the work done after reauthenticating

TODO

• When receiving a 401 unauthorized response code or having a timeout on a save request (for a start 10 seconds without having an answer should do it)
  • Open a modal popup (i.e. popup can be closed)
  • Containing the following text:

    (Nuxeo logo) Online Services
    Your session timed out or your lost connectivity, and your work is not saved yet. Please [reauthenticate](link to reauthentication that opens in a new tab)" and try saving again.

• When clicking the link, a dedicated page is opened in a new tab => if user is actually logged out she will be taken to sso and redirected to this page after auth is successful, if user is still logged in the page will display normally.
  • This page contains the following text:

    (Nuxeo logo) Online Services
    You have successfully been reauthenticated and can [close this window](link - when clicking, triggers a js to close the tab) now.

ACCEPTANCE CRITERIA

• Popup is triggered when user is logged out and trying to:
  • save in Studio Modeler
  • save in Studio Designer
  • trying to do any Git action like commit, push, pull

• Popup is triggered after 10 seconds when user has lost connectivity and is trying to:
  • save in Studio Modeler
  • save in Studio Designer
  • trying to do any Git action like commit, push, pull

• Popup prevents the action to be done
  • e.g. if I want to pull but I am logged out, I get this popup instead of the pull dialog.
  • same with commit / push dialogs

• Popup contains the correct text
• Popup can be closed
• Link to reauthentication opens in a new tab
• If user is logged out, reauthentication link takes user to SSO
• After logging back in using form auth, user is redirected to the success page
• After logging back in using Google, user is redirected to the success page
• Clicking the close link closes the tab containing the success page (behavior may differ between browsers - that's ok if it asks confirmation to the user, the point is it should try to do it)
• After successful reauthentication, user can save again without triggering the reauthentication popup
• After successful reauthentication, user can execute git actions again without triggering the reauthentication popup