AUTH-2077: Quotes open browser command in windows

cmd/cloudflared/shell/launch_browser_windows.go

@@ -0,0 +1,18 @@
+//+build windows
+
+package shell
+
+import (
+	"fmt"
+	"os/exec"
+	"syscall"
+)
+
+func getBrowserCmd(url string) *exec.Cmd {
+	cmd := exec.Command("cmd")
+	// CmdLine is only defined when compiling for windows.
+	// Empty string is the cmd proc "Title". Needs to be included because the start command will interpret the first
+	// quoted string as that field and we want to quote the URL.
+	cmd.SysProcAttr = &syscall.SysProcAttr{CmdLine: fmt.Sprintf(`/c start "" "%s"`, url)}
+	return cmd
+}