[Feature]: Use system default editor to edit manifest file

[gili-gili]

Summary

Unable to edit manifest if you have Notepad uninstalled, even if a editor is specified as the default application to edit .manifest files.
It's also a problem for those who want use other editors for more features (e.g syntax highlighing, auto-completion).

Pitch

Screenshot

Log

[5/26/2023 4:55:59] [Warning] Error occurred while working on the manifest file. System.ComponentModel.RunWorkerCompletedEventArgs
[5/26/2023 4:55:59] [Warning] Error Occurred: System.ComponentModel.Win32Exception (0x80004005): The system cannot find the file specified
   at System.Diagnostics.Process.StartWithShellExecuteEx(ProcessStartInfo startInfo)
   at MsixPackagingTool.ViewModel.PackageEditorWorkflow.PackageInformationViewModel.OpenManifestFileProcess(InstallerHelper installerHelper)
   at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
   at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)

[lilybarkley-msft]

Thanks for reporting this issue, we'll get this feature request over to our partners in the MPT team.