Add authentication system tests

[Ikuze]

Hello,

I added some system tests in order to test that the cookie functionality is working properly.

jenkins_admin_admin fixture will connect to jenkins and will create a user (admin/admin) with admin permissions. Anonymous will have no permissions at all, that way we can check if the authentication is working or not.

jenkins_admin_admin fixture disables the security everytime a test ends, restoring the original state.

We test that:

• test_normal_uthentication: Normal authentication (without taking the cookie into account) is working.
• test_auth_cookie: We can login and get the cookie properly.
• test_wrongauth_cookie: If the user/pass is wrong, we verify that actually it fails and we cannot get the cookie.
• test_verify_cookie_isworking: The cookie that we are getting is actually useful and we are authenticated in jenkins as long as we have the cookie, even if the requester has no user/pass.

BR.

[codecov[bot]]

Codecov Report

Merging #686 into master will increase coverage by 0.37%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #686      +/-   ##
==========================================
+ Coverage   78.52%   78.89%   +0.37%     
==========================================
  Files          34       34              
  Lines        2682     2682              
==========================================
+ Hits         2106     2116      +10     
+ Misses        576      566      -10