Feature expand health endpoint reporting

[JH-A-Kim]

---

Description

These changes act as an implementation for the suggested changes in the design proposal:

Design propsoal

and from the Discussion from the following thread and lazy consensus on the dev list:

DISCUSS
LAZY CONSENSUS

These changes were co authored by @JH-A-Kim and @Tegh25

The changes are the following:

• extended monitor.py to support instances and detailed status reporting in the JSON output for the health endpoint
• added helper functions to get information from the metadata database for running components, aggregate statuses from a list of component instances, and a legacy health reporter.
• extended get_airlfow_health to include lists of components and report their aggregated status.
• added aggregated status reporting in a three tier model for detailed_status, healthy > degraded > unhealthy. These are all instances are healthy, at least one instance is healthy and at least one is unhealthy, and then unhealthy is where all instances are down.

Was generative AI tooling used to co-author this PR?

• Yes (please specify the tool below)

Generated-by: [Sonnet 5] following the guidelines

---

• Read the Pull Request Guidelines for more information. Note: commit author/co-author name and email in commits become permanently public when merged.
• For fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
• When adding dependency, check compliance with the ASF 3rd Party License Policy.
• For significant user-facing changes create newsfragment: {pr_number}.significant.rst, in airflow-core/newsfragments. You can add this file in a follow-up commit after the PR is created so you know the PR number.