feat: add docs bundle test runners

[AlexanderLanin]

Summary

• add a testonly <bundle>_tests companion target for docs_bundle(tests = [...])
• run direct and nested XML_OUTPUT_FILE-compliant test executables without making documentation targets testonly
• make score_pytest honor XML_OUTPUT_FILE when invoked by the companion runner

Validation

• bazel test //src/tests/docs_bzl/scenarios/nested_bundles:parent_tests --test_output=errors
• .venv_docs/bin/python -m pytest -q src/tests/docs_bzl/test_nested_bundles.py
• bazel test //score_pytest:test_rules_are_working_correctly --test_output=errors

[github-actions]

License Check Results

🚀 The license check job ran with the Bazel command:

bazel run --lockfile_mode=error //src:license-check

Status: ⚠️ Needs Review

Click to expand output

[License Check Output]
Extracting Bazel installation...
Starting local Bazel server (8.6.0) and connecting to it...
INFO: Invocation ID: 99be6c2d-e410-4058-98ca-03e07734f1ea
Computing main repo mapping: 
Loading: 
Loading: 0 packages loaded
Loading: 0 packages loaded
Loading: 0 packages loaded
    currently loading: src
WARNING: Target pattern parsing failed.
ERROR: Skipping '//src:license-check': no such target '//src:license-check': target 'license-check' not declared in package 'src' defined by /home/runner/work/docs-as-code/docs-as-code/src/BUILD
ERROR: no such target '//src:license-check': target 'license-check' not declared in package 'src' defined by /home/runner/work/docs-as-code/docs-as-code/src/BUILD
INFO: Elapsed time: 5.686s
INFO: 0 processes.
ERROR: Build did NOT complete successfully
ERROR: Build failed. Not running target

[github-actions]

The created documentation from the pull request is available at: docu-html