Rails app:update: missing migrations

We don't use ActiveStorage in this app, but app:update detected these
migrations were missing so I feel it's better to add them for now.

We can more fully remove ActiveStorage from this app in the future, but
I was not prepared to address that during this maintenance cycle.

Author: JPrevost

db/migrate/20240228201654_add_service_name_to_active_storage_blobs.active_storage.rb

@@ -0,0 +1,22 @@
+# This migration comes from active_storage (originally 20190112182829)
+class AddServiceNameToActiveStorageBlobs < ActiveRecord::Migration[6.0]
+  def up
+    return unless table_exists?(:active_storage_blobs)
+
+    unless column_exists?(:active_storage_blobs, :service_name)
+      add_column :active_storage_blobs, :service_name, :string
+
+      if configured_service = ActiveStorage::Blob.service.name
+        ActiveStorage::Blob.unscoped.update_all(service_name: configured_service)
+      end
+
+      change_column :active_storage_blobs, :service_name, :string, null: false
+    end
+  end
+
+  def down
+    return unless table_exists?(:active_storage_blobs)
+
+    remove_column :active_storage_blobs, :service_name
+  end
+end

db/migrate/20240228201655_create_active_storage_variant_records.active_storage.rb

@@ -0,0 +1,27 @@
+# This migration comes from active_storage (originally 20191206030411)
+class CreateActiveStorageVariantRecords < ActiveRecord::Migration[6.0]
+  def change
+    return unless table_exists?(:active_storage_blobs)
+
+    # Use Active Record's configured type for primary key
+    create_table :active_storage_variant_records, id: primary_key_type, if_not_exists: true do |t|
+      t.belongs_to :blob, null: false, index: false, type: blobs_primary_key_type
+      t.string :variation_digest, null: false
+
+      t.index %i[ blob_id variation_digest ], name: "index_active_storage_variant_records_uniqueness", unique: true
+      t.foreign_key :active_storage_blobs, column: :blob_id
+    end
+  end
+
+  private
+    def primary_key_type
+      config = Rails.configuration.generators
+      config.options[config.orm][:primary_key_type] || :primary_key
+    end
+
+    def blobs_primary_key_type
+      pkey_name = connection.primary_key(:active_storage_blobs)
+      pkey_column = connection.columns(:active_storage_blobs).find { |c| c.name == pkey_name }
+      pkey_column.bigint? ? :bigint : pkey_column.type
+    end
+end

db/migrate/20240228201656_remove_not_null_on_active_storage_blobs_checksum.active_storage.rb

@@ -0,0 +1,8 @@
+# This migration comes from active_storage (originally 20211119233751)
+class RemoveNotNullOnActiveStorageBlobsChecksum < ActiveRecord::Migration[6.0]
+  def change
+    return unless table_exists?(:active_storage_blobs)
+
+    change_column_null(:active_storage_blobs, :checksum, true)
+  end
+end