…eline (#23687)

* Restore legacy datadog_checks_dev jmx_metrics file to fix release pipeline

PR #23652 deleted datadog_checks_dev/datadog_checks/dev/tooling/commands/validate/jmx_metrics.py
when migrating the command to ddev. The most recent in-toto tag link
(.in-toto/tag.4e75cfa1.link) still lists this file as a product, so the
wheels-builder materials assertion in record_materials.py fails the build.

Restore the file with its original byte-identical content so the in-toto
check passes. The file stays unregistered in the validate group, so ddev
keeps owning the `validate jmx-metrics` command. The file can be removed
again once the next datadog_checks_dev release rotates the tag link.

* Restore validate group __init__ and add changelog entry

The validate group's __init__.py is also recorded in tag.4e75cfa1.link
with the pre-#23652 hash, so the in-toto chain verification would fail
without restoring its content too. The re-registered command is dead
code: ddev keeps owning `validate jmx-metrics`.

Splits the single-file `ddev/utils/github_async.py` into a package with the
client and HTTP-shape primitives in `client.py` and one model per submodule
under `models/`. Both `__init__.py` files use PEP 562 module-level
`__getattr__` so importing one symbol only loads the submodule that defines
it -- in particular `from ddev.utils.github_async.models import PullRequest`
does not pull in the workflow or comment models.

Adds two new endpoints used by upcoming work:
  - `AsyncGitHubClient.create_pull_request(owner, repo, title, head, base, body, draft)`
  - `AsyncGitHubClient.add_labels_to_issue(owner, repo, issue_number, labels)`

Expands the `PullRequest` model with the typical fields callers need (id,
state, draft, title, body, user, assignees, requested_reviewers, labels,
created_at/updated_at/closed_at/merged_at, head, base) plus three small
sub-models (`GitHubUser`, `Label`, `PullRequestRef`). Only `number` and
`html_url` are required; the rest default to None/[] so partial payloads
parse fine and `extra='ignore'` keeps the schema forward-compatible.

Adds `FakeAsyncGitHubClient` and the `fake_async_github` pytest fixture in
`tests/helpers/github_async.py`. The fake records every call and offers
`mock_response(method, response, /, *, once=False, **match_kwargs)` for
stubbing replies. Responses can be `BaseException` instances (raised),
`GitHubResponse` instances (passed through), or inner data (auto-wrapped).
`once=True` adds to a per-method FIFO queue so tests can model retry
sequences. Sticky mocks (no `once`) match the most-recent registration.
`assert_called_with` / `assert_called_once_with` perform strict-equality
checks on kwargs; `assert_all_responses_consumed()` asserts the one-shot
queue was drained.

* Add ddev release port-commit command

* Lowercase port branch name and clean up step output

* Improve port-commit output: split steps, lighter styling, completion panel, commit link in PR body