Stabilize the behavior and reliability of ExternalProcessService (#1212)

* Stabilize the behavior and reliability of ExternalProcessService

* Apply suggestions from code review

Co-authored-by: Patrick Hallisey <hallipr@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Follow .editorconfig naming, remove the race in dispose

* rename executablePath to fileName

* add exception documentation to ExecuteAsync

---------

Co-authored-by: Patrick Hallisey <hallipr@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: 3 people