Add email subject to password reset request email

[pierredup]

No description provided.

[what-the-diff]

PR Summary

• Introduction of a Subject Line in Password Reset Emails
  This change ensures that every email sent to users for password reset requests now includes a subject line. This will make these emails more recognisable and easier to search for in users' inboxes, improving user experience.

[codecov]

Codecov Report

Patch coverage: 66.66% and project coverage change: -0.02% ⚠️

Comparison is base (5d115d0) 50.97% compared to head (1e1ae3b) 50.95%.
Report is 6 commits behind head on 2.2.x.

Additional details and impacted files

@@             Coverage Diff              @@
##              2.2.x     #934      +/-   ##
============================================
- Coverage     50.97%   50.95%   -0.02%     
  Complexity     2229     2229              
============================================
  Files           442      442              
  Lines          8295     8295              
============================================
- Hits           4228     4227       -1     
- Misses         4067     4068       +1     

Flag	Coverage Δ
unittests	50.95% <66.66%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
src/UserBundle/Email/ResetPasswordEmail.php	0.00% <0.00%> (ø)
src/MailerBundle/Factory/MailerConfigFactory.php	87.50% <100.00%> (-0.74%)	⬇️

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