AuthService: Throw error if pop-up windows are blocked

[kkangs0226]

Fixes #636

Summary

Pop-up windows are blocked by default on Safari. This causes the authentication window to be blocked, causing users to be stuck on loading screen without any notification.

Changes Made

• Error message has been added to inform users to enable pop-up windows in their browser
• Users are brought back to the previous select session page instead of loading screen

Proposed commit message:

AuthService: Throw error message if pop-up windows are blocked

The authentication window is blocked by default in Safari, causing
users to be stuck on loading screen without any notification.

Showing error message to notify users to enable pop-ups and
then directing them back to the start of authentication will
make our application more user-friendly.

Let's
* Show error message when pop-ups are blocked
* Restart authentication process

[codecov-io]

Codecov Report

Merging #647 (1a3edcc) into master (0be2b05) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #647   +/-   ##
=======================================
  Coverage   67.72%   67.72%           
=======================================
  Files          75       75           
  Lines        2259     2259           
  Branches      207      207           
=======================================
  Hits         1530     1530           
  Misses        686      686           
  Partials       43       43           

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