feat: implement patching of task group instances in API

[OscarLigthart]

Context

In Airflow 3 the ability to mark a full task group as failed or success is currently missing. In this PR, I try to implement the logic into the API, that can then be called from the frontend to ensure the functionality returns.

I deliberately split the feature in two separate PRs, so the reviewing process can be more targeted to the individually touched components. Should this PR get merged, I will continue to build the remaining requirements into the frontend.

There is an already open PR here: #60161

However, it looks to be stale, and I would love to get this feature into the Airflow 3.2 release.

Implementation

I make use of the BulkTaskInstanceService to perform the state updates with this endpoint. Using it, the implementation should be pretty straightforward :).

Issues

related: #56103

---

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

• Yes (please specify the tool below)

Generated-by: Claude Opus 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 or {issue_number}.significant.rst, in airflow-core/newsfragments.