Allow members-restricted posts to be viewable by instance moderators

But add a warning message on top of the post

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

js/tests/unit/specs/components/Group/GroupSection.spec.ts

@@ -16,7 +16,7 @@ const groupDomain = "remotedomain.net";
 const groupUsername = `${groupPreferredUsername}@${groupDomain}`;
 
 const defaultSlotText = "A list of elements";
-const createSlotButtonText = "+ Post a public message";
+const createSlotButtonText = "+ Create a post";
 
 type Props = {
   title?: string;