French translation for user registered message

[josegar74]

Test case:

Steps to recreate:

• use the french interface
• click sign in / s'identifier
• click create an account / créer un compte
• fill in the registration form and click register / créer un compte
• a blue message box pops up in the top, left corner with the message in English: "User '[email address]' registered."

With the pull request in the French user interface, it is displayed the message: "Utilisateur '[email address]' enregistré."

Checklist

• I have read the contribution guidelines
• Pull request provided for main branch, backports managed with label
• Good housekeeping of code, cleaning up comments, tests, and documentation
• Clean commit history broken into understandable chucks, avoiding big commits with hundreds of files, cautious of reformatting and whitespace changes
• Clean commit messages, longer verbose messages are encouraged
• API Changes are identified in commit messages
• Testing provided for features or enhancements using automatic tests
• User documentation provided for new features or enhancements in manual
• Build documentation provided for development instructions in README.md files
• Library management using pom.xml dependency management. Update build documentation with intended library use and library tutorials or documentation

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}