Navigate to Login page on invalid session token

[JoelWiebe]

Completed

• Extended session duration from 2h to 4h
• Modified API Interceptor to navigate to login page on 401 error
• Modified invalid token error to throw 401 error

Test

• Verify no unusual browser console or backend errors (other than the one or two 401 errors thrown immediately at the time a resource is requested when the session token has expired)
• Ensure navigation is routed to the login page when the session expires and a resource is requested

To test, you may need to rebuild the backend and it will be helpful to adjust the session token duration

• Search all files and replace three instances of '4h' with '1m' so that the session will expire after 1 minute
• In backend perform: "rm -r node_modules; npm install; npm run dev" to rebuild
• Login and wait for just over a minute, then attempt to navigate to another page or create a post
• You should be navigated back to the login page with a 401 error

Closes #651

[markiianbabiak]

This is the page I got instead of the login page.

To recreate:
Login, go to any board, go to canvas, wait, try switching to workspace.

Side note: consider also showing a pop-up message at the top saying "Session expired. Redirected to login page"