Add consumer-based RfC Visibility settings

This setting will be useful to increase data protection, where users might not be allowed to see RfCs from other contexts.

db/migrate/20230219113125_add_rfc_visibility_to_consumer.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddRfcVisibilityToConsumer < ActiveRecord::Migration[7.0]
+  def change
+    add_column :consumers, :rfc_visibility, :integer, limit: 1, null: false, default: 0, comment: 'Used as enum in Rails'
+  end
+end