Linux/macOS: show volume creation finalization stages

Report explicit progress stages while writing volume data, writing backup headers, and flushing data to disk so the wizard does not appear stuck at 100%.

Keep the wizard in progress during Unix post-creation formatting and show status for temporary mount/device setup, mkfs invocation, and dismount.

src/Main/Forms/VolumeCreationWizard.h

@@ -59,6 +59,7 @@ namespace VeraCrypt
 		void OnThreadExiting (wxCommandEvent& event);
 		void OnVolumeCreatorFinished ();
 		WizardStep ProcessPageChangeRequest (bool forward);
+		void SetCreationProgressText (const wxString &text);
 
 		volatile bool AbortConfirmationPending;
 		volatile bool AbortRequested;