FEATURE: Hide user status when user is hiding public profile and presence (#24300)

Users can hide their public profile and presence information by checking 
“Hide my public profile and presence features” on the 
`u/{username}/preferences/interface` page. In that case, we also don't 
want to return user status from the server.

This work has been started in https://github.com/discourse/discourse/pull/23946. 
The current PR fixes all the remaining places in Core.

Note that the actual fix is quite simple – a5802f484d. 
But we had a fair amount of duplication in the code responsible for 
the user status serialization, so I had to dry that up first. The refactoring 
as well as adding some additional tests is the main part of this PR.

spec/serializers/user_with_custom_fields_serializer_spec.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+RSpec.describe UserWithCustomFieldsSerializer do
+  describe "#status" do
+    fab!(:user_status)
+    fab!(:user) { Fabricate(:user, user_status: user_status) }
+
+    it "adds user status when enabled in site settings" do
+      SiteSetting.enable_user_status = true
+
+      serializer =
+        described_class.new(user, scope: Guardian.new(user), root: false, include_status: true)
+      json = serializer.as_json
+
+      expect(json[:status]).to be_present
+    end
+  end
+end