DAG-Level View for Asset Emissions and Task Artifacts

### Description

Add a consolidated artifact view on the DAG Details page (the page accessed by selecting a DAG from the left-side “DAGs” tab).

This view should display, at the DAG run level:

All assets emitted by the DAG

The originating task for each asset

Asset emission events

Other relevant task-level artifacts (e.g., rendered templates)

The goal is to surface task-emitted artifacts directly in the DAG run context, without requiring users to click into individual task instances.

This would make asset-driven workflows more observable and significantly reduce friction when debugging or inspecting DAG outputs.

### Use case/motivation

In large DAGs with many tasks or nested task groups, it’s difficult to trace where an asset event or other task-level artifact originated. Today, users must drill into individual task instances to find emitted assets, rendered templates, and related artifacts.

As Airflow shifts toward asset-driven workflows, asset emissions become a core concept—not a secondary detail buried inside task instances. Users need a clear, centralized way to understand what a DAG produced and which task produced it. Making asset emissions more visible at the DAG level improves debuggability, traceability, and overall usability for complex pipelines.

### Related issues

_No response_

### Are you willing to submit a PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)