[Feature Request] detect session timeout/logout in JS

[olaulau]

Describe what you don't like about Ampache, or what it is missing

when pausing web play for a long time, session timeout could occur.
then the next song will not play (as it won't be able to download it). refreshing the whole page shows that we have been logged out.

Describe how you would like the feature to work**

• get the correct error from AJAX queries
• redirect the user to authentication page