Better handle indications that the auth token may have expired

[phantomjinx]

Logging in with a token, especially when using form authentication, requires entering a token that may have been generated using create token <service-account>. Such tokens can have quite short lifetimes hence expire. However, expiration is not necessarily tested when authenticating and the token may actually expire after logging-in. Such a use-case results in no pods being displayed in Discover due to error 401 responses being returned from requests to the cluster API server.

Better information informing the user with some kind of warning that the token may need renewing (if not renewing automatically) would be beneficial.