DEV: Make experimental sidebar site settings public (#17921)

This commits makes the `enable_experimental_sidebar_hamburger` and
`enable_sidebar` site settings public for site admins to enable. While
the site settings are public, do note that the features are still under
heavy development and are subjected to rapid changes

config/locales/server.en.yml

@@ -1794,6 +1794,8 @@ en:
     top_topics_formula_least_likes_per_post_multiplier: "value of least likes per post multiplier (n) in top topics formula: `log(views_count) * 2 + op_likes_count * 0.5 + LEAST(likes_count / posts_count, (n)) + 10 + log(posts_count)`"
 
     enable_safe_mode: "Allow users to enter safe mode to debug plugins."
+    enable_experimental_sidebar_hamburger: "Allows experimental sidebar and user hamburger dropdown menu to be enabled."
+    enable_sidebar: "Enables experimental sidebar."
 
     rate_limit_create_topic: "After creating a topic, users must wait (n) seconds before creating another topic."
     rate_limit_create_post: "After posting, users must wait (n) seconds before creating another post."

config/site_settings.yml

@@ -1988,11 +1988,9 @@ developer:
   enable_experimental_sidebar_hamburger:
     default: false
     client: true
-    hidden: true
   enable_sidebar:
-    default: false
+    default: true
     client: true
-    hidden: true
 
 embedding:
   embed_by_username: