preserve current location when redirecting to login

[ChristopherChudzicki]

What are the relevant tickets?

Small followup to #319

Description (What does it do?)

In #319, when a user logged in, they would be redirected to the homepage. Instead, this PR preserves the current page.

How can this be tested?

Prerequisites: Connect your local instance to keycloak; either local keycloak or on RC. Ask me for creds if you need them.

Assuming you are initially unauthenticated:

1. As an unauthenticated user, visit http://localhost:8063/learningpaths?pup=woof The search parameters don't do anything, but let's check that they get preserved.
2. In top right, click log in, and log in via keycloak.
3. After logging in, you should be redirected to the page you were on (http://localhost:8063/learningpaths?pup=woof)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (8299378) 76.76% compared to head (b1c9306) 76.81%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #330      +/-   ##
==========================================
+ Coverage   76.76%   76.81%   +0.05%     
==========================================
  Files         282      282              
  Lines       13134    13141       +7     
  Branches     2152     2154       +2     
==========================================
+ Hits        10082    10094      +12     
+ Misses       2823     2819       -4     
+ Partials      229      228       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[collinpreston]

Works well, nice!