Enable minidumps on all helix runs. (dotnet/coreclr#26455)
* Set COMPlus_DbgEnableMiniDump on all helix test runs.
* Set dump output path for *nix builds.
* Enable collecting dumps for timed-out tests on Windows.
* Enable xunit wrapper to get dumps for timed-out tests on non-Windows.
* Use sudo for createdump
* Update coredump-on-crash pattern to use the $HELIX_WORKITEM_UPLOAD_ROOT environment variable.
* Implement linux-specific path for finding a child process by name.
* Use HELIX_DUMP_FOLDER instead of HELIX_WORKITEM_UPLOAD_ROOT
* Remove empty entries in childrenPidAsStrings.
* Look up createdump in Core_Root
* Implement timeout macOS crash dumps.
* Add ulimit -c unlimited to the Helix script on MacOS.
* Get MacOS timeout dumps working (and enable assert/exception dumps)
* Copy OSX aborted test dumps to crash dump folder.
* Add missing return true.
* Allow overwriting dump files on copy (on macOS).
* Fix accidental shadow.
* Allow multiple spaces in ps output.
* Fix dump on windows hitting an assert on checked coreclr.
* TEMPORARY: Add more logging in macOS case.
* Fix change.
* Fix macOS timeout crash dump creation (at least locally).
* Fix Windows timeout dump collection.
* Explicitly use WChar structures.
* TEMPORARY: Test OSX dumps on 10.14 queue.
* Fix __CrashDumpFolder on OSX
* Don't try to copy the dump if it doesn't exist (10.13 Helix queue doesn't support it yet).
* Remove temporary OSX 10.14 queue usage in prs.
* Add tracking issue for empty HELIX_DUMP_FOLDER env var on OSX.
* PR Feedback
Commit migrated from https://github.com/dotnet/coreclr/commit/
f5437ac095272f1ab5e8ca79960add974fa96f2d