Add parallel execution tests and improve cancellation handling in `CliRunner`
- Introduced new tests (`RunMultipleTimesTestProgram_CheckParalelWork` and `RunMultipleTimesTestProgram_CheckParalelWorkCumulative`) to verify parallel execution behavior.
- Enhanced `SendAsync` and `RunAndCaptureJsonAsync` methods in `CliRunner` with `CancellationToken` support for better task cancellation.
- Refactored process output handling for improved clarity and robustness.
- Added error handling during CLI logger initialization.