Support stdinOnce, which allows run-once STDIN injection

This allows containers to wait for input before startup by listening
on STDIN, and after STDIN is closed, continue running. Matches the
Docker syntax.

pkg/api/deep_copy_generated.go

@@ -238,6 +238,7 @@ func deepCopy_api_Container(in Container, out *Container, c *conversion.Cloner)
 		out.SecurityContext = nil
 	}
 	out.Stdin = in.Stdin
+	out.StdinOnce = in.StdinOnce
 	out.TTY = in.TTY
 	return nil
 }