Modify Authentication Flows

[keiffer01]

Issue summary

See differences between expected and actual behavior.

Expected behavior

• When the user is already authenticated, they should be automatically redirected to the VIEW_TRIPS page if they go to the SIGN_IN page.
• When the user clicks the Sign Out button, they should be redirected to the LANDING page.

Actual behavior

• An already authenticated user that navigates to the SIGN_IN page will not be automatically redirected to their trips page.
• When the user clicks the Sign Out button, they are redirected to the SIGN_IN page instead of the LANDING page.

Steps to reproduce (including any preconditions)

As described in the expected behavior section.