feat: Use inbox image as avatar for the bot (#6859)

db/migrate/20230407191457_migrate_env_var_to_channel_feature.rb

@@ -0,0 +1,12 @@
+class MigrateEnvVarToChannelFeature < ActiveRecord::Migration[6.1]
+  def change
+    return unless ActiveModel::Type::Boolean.new.cast(ENV.fetch('USE_INBOX_AVATAR_FOR_BOT', false))
+
+    Channel::WebWidget.find_in_batches do |widget_batch|
+      widget_batch.each do |widget|
+        widget.use_inbox_avatar_for_bot = true
+        widget.save!
+      end
+    end
+  end
+end