webui: handle back button when unauthenticated
using browser history when unauthenticated causes transition to
the original and/or preceding facets. But nothing works since
all commands fail due to expired credentials in session.
These changes make sure that user stays on login screen if he misses
valid session credentials while he wants to switch to facet which
Reviewed-By: Endi Sukma Dewata <email@example.com>