Fix issue with --dest-dir for CI usage

[tjprescott]

Updates the CI package checks so that it targets the right folder which maintaining the contract that apistub --dest-dir X actually targets X.

[Copilot]

Pull request overview

This PR fixes how the CI check dispatcher (eng/scripts/dispatch_checks.py) computes the --dest-dir passed to the apistub check. Previously it passed the shared artifact staging directory directly, but the downstream Create-APIReview.ps1 step looks for the generated APIView token file under a per-package subfolder ($ArtifactPath/$packageName/${packageName}_python.json). The fix appends the package name to the destination for apistub only, keeping the apistub --dest-dir X contract intact (it still writes exactly where told) while producing the folder layout CI consumers expect.

Changes:

• Add get_check_dest_dir helper that appends the resolved package name to dest_dir for the apistub check and returns it unchanged otherwise.
• Wire the helper into run_check so the apistub command targets the per-package subdirectory.
• Add unit tests for the new helper and for the generate_api_for_package command construction in the API-review workflow.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
eng/scripts/dispatch_checks.py	Imports ParsedSetup, adds get_check_dest_dir, and uses it to compute the per-package --dest-dir for apistub.
eng/tools/azure-sdk-tools/tests/test_dispatch_checks.py	New tests covering apistub subfolder behavior, non-apistub pass-through, and empty dest-dir handling.
scripts/api_md_workflow/create_api_review_pr_test.py	Adds tests asserting generate_api_for_package builds the apistub --dest-dir <package_dir> command for both azpysdk and runtime-executable paths.

[danieljurek]

This fixes the issue it intended to fix: https://dev.azure.com/azure-sdk/internal/_build/results?buildId=6508343&view=logs&j=b70e5e73-bbb6-5567-0939-8415943fadb9&t=f14f2bed-72ab-5062-192c-a977bd0d104b&l=58

There are other failures, but they look related to mypy and azure-template... so I would not consider those blocking based on what I'm seeing.