[BUG] Auth not handling Minecraft username change

**Describe the bug**
Minecraft offers the possibility to change username every 30 days. ATM, the application doesn't handle this changes :
It will try to re-create a new account, conducting to a security, or a duplicate userId error.

**To Reproduce**
Steps to reproduce the behavior:
1. Try to login with a MS account
2. Logout
3. Change your MC username (or, for testing purposes, just go to auth.ts => in returned object of profile function, set name to a dummy value)
4. See error

**Expected behavior**
User should log in smoothly, and its username should be updated in the database

**Screenshots**
*None*

**Desktop (please complete the following information):**
- OS: any
- Browser any
- Version pre-release

**Additional context**
*None*