Implement email verification feature, add registration form, and update user entity for verification status

config/packages/mailer.yaml

@@ -0,0 +1,7 @@
+framework:
+  mailer:
+    dsn: '%env(MAILER_DSN)%'
+    envelope:
+      sender: '%env(MAILER_SENDER)%'
+    headers:
+      From: 'Tijd voor de test <%env(MAILER_SENDER)%>'