Add foreign key to active_storage_attachments for `blob_id` via new migration

We need this in order to be able to add this migration for users that
use ActiveStorage during update their apps from Rails 5.2 to Rails 6.0.

Related to #33405

`rake app:update` should update active_storage

`rake app:update` should execute `rake active_storage:update`
if it is used in the app that is being updated.
It will add new active_storage's migrations to users' apps during update Rails.

Context https://github.com/rails/rails/pull/33405#discussion_r204239399

Also, see a related discussion in the Campfire:
https://3.basecamp.com/3076981/buckets/24956/chats/12416418@1236713081

1 files changed, 5 insertions, 1 deletions

diff --git a/railties/lib/rails/tasks/framework.rake b/railties/lib/rails/tasks/framework.rake
index 1a3711c446..2886986865 100644
--- a/railties/lib/rails/tasks/framework.rake
+++ b/railties/lib/rails/tasks/framework.rake
@@ -2,7 +2,7 @@
 
 namespace :app do
   desc "Update configs and some other initially generated files (or use just update:configs or update:bin)"
-  task update: [ "update:configs", "update:bin", "update:upgrade_guide_info" ]
+  task update: [ "update:configs", "update:bin", "update:active_storage", "update:upgrade_guide_info" ]
 
   desc "Applies the template supplied by LOCATION=(/path/to/template) or URL"
   task template: :environment do
@@ -51,6 +51,10 @@ namespace :app do
       Rails::AppUpdater.invoke_from_app_generator :update_bin_files
     end
 
+    task :active_storage do
+      Rails::AppUpdater.invoke_from_app_generator :update_active_storage
+    end
+
     task :upgrade_guide_info do
       Rails::AppUpdater.invoke_from_app_generator :display_upgrade_guide_info
     end