Improve notification_metadata in Ash.Reactor DSLs

[meeq]

Stacked on top of #2449

(Please review #2449 first: it establishes test cases which ensure that this PR does not break existing usage of notification_metadata on bulk_create and bulk_update steps.)

Changes

• Add notification_metadata support to Ash.Reactor create, update, and delete steps.
• Enhance notification_metadata on Ash.Reactor bulk_create and bulk_update steps to support transform.
• Clean up Ash.Reactor formatting in any test files that I touched

Contributor checklist

Leave anything that you believe does not apply unchecked.

• I accept the AI Policy, or AI was not used in the creation of this PR.
• Bug fixes include regression tests
• Chores
• Documentation changes
• Features include unit/acceptance tests
• Refactoring
• Update dependencies