feat: Add support for URL query search

[fcole90]

I noticed that the courses page has support for adding tags and a few other URL params, but is missing any search param.
I think that can be useful for sharing and link purposes: e.g. https://www.mooc.fi/en/courses/?status=Active&search=cybersecurity
y
This PR adds support for that!

Unfortunately I got many issues when setting up the environment, and the pre-commit hook kept failing, even if npm run prettier worked correctly (after I deleted backend/.prettierrc.js as that was incorrectly set to ../.prettierrc).
So, for all such reasons, I wasn't able to properly test this, so I'd need some help, either with someone else testing this or helping me set this up correctly.

Great work with all the MOOC initiative, that's an amazing opportunity! 😃

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.44%. Comparing base (55af797) to head (d547a1c).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1283   +/-   ##
=======================================
  Coverage   66.44%   66.44%           
=======================================
  Files         144      144           
  Lines        6046     6046           
  Branches     1437     1437           
=======================================
  Hits         4017     4017           
  Misses       1890     1890           
  Partials      139      139           

Flag	Coverage Δ
backend	66.44% <ø> (ø)

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[fcole90]

CI is unfortunately failing, it seems like CircleCI is missing a configuration file 😕