✨(backend) add user abilities for front

This allows, on a per user basis, the display of
features.

The main goal here is to allow Team admin or owner
to see the management views.
We also added the same for the two other features
(mailboxes and contacts)

This will be improved later if needed :)

src/backend/people/settings.py

@@ -451,18 +451,33 @@ class Base(Configuration):
         )
     )
 
-    FEATURES = {
-        "TEAMS": values.BooleanValue(
-            default=True, environ_name="FEATURE_TEAMS", environ_prefix=None
-        ),
-    }
-
     # pylint: disable=invalid-name
     @property
     def ENVIRONMENT(self):
         """Environment in which the application is launched."""
         return self.__class__.__name__.lower()
 
+    # pylint: disable=invalid-name
+    @property
+    def FEATURES(self):
+        """Feature flags for the application."""
+        FEATURE_FLAGS: set = {
+            "CONTACTS_CREATE",  # Used in the users/me/ endpoint
+            "CONTACTS_DISPLAY",  # Used in the users/me/ endpoint
+            "MAILBOXES_CREATE",  # Used in the users/me/ endpoint
+            "TEAMS",
+            "TEAMS_CREATE",  # Used in the users/me/ endpoint
+        }
+
+        return {
+            feature: values.BooleanValue(
+                default=True,
+                environ_name=f"FEATURE_{feature}",
+                environ_prefix=None,
+            )
+            for feature in FEATURE_FLAGS
+        }
+
     # pylint: disable=invalid-name
     @property
     def RELEASE(self):