Added sidecar mechanism for hard-fault-/thread-kill-tolerant CI test logging

[Micky774]

Description

The CI test summary (junit_report.py) is a pure aggregator of JUnit XML files, but pytest writes its --junitxml only at session end so a --timeout-method=thread firing, segfault, or OOM-kill that os._exit()s the process produces no XML for that file, and the summary silently drops it and shows green even though the suite exit-code gate correctly fails.

This change closes that gap on two levels:

(1) a new te_ci_result_sink pytest plugin streams each test's progress to a <junitxml>.partial sidecar (flushed per line, deleted on clean exit), which junit_report.py reconstructs when a run hard-exits, preserving pre-crash passes and surfacing the in-flight test as a [timeout]

(2) as a floor, pytest_run now synthesizes a minimal error report when pytest exits non-zero without writing any XML at all (e.g. usage/conftest-import errors before the plugin loads), so the summary always stays consistent with the pass/fail gate. Verified end-to-end against real thread-method timeouts, conftest errors, normal failures, and clean passes.

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Infra/Build change
• Code refactoring

Changes

Please list the changes introduced in this PR:

• Change A
• Change B

Checklist:

• I have read and followed the contributing guidelines
• The functionality is complete
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes