Add executable file `activestorage/bin/test`

```
rails$ cd activestorage/
rails/activestorage$ bin/test
........(compressed)....
rails/activestorage$ bin/test test/controllers/disk_controller_test.rb
.(compressed)..
rails/activestorage$ bin/test test/controllers/disk_controller_test.rb:42
.
```

1 files changed, 5 insertions, 0 deletions

diff --git a/activestorage/bin/test b/activestorage/bin/test
new file mode 100755
index 0000000000..c53377cc97
--- /dev/null
+++ b/activestorage/bin/test
@@ -0,0 +1,5 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+COMPONENT_ROOT = File.expand_path("..", __dir__)
+require_relative "../../tools/test"