feat: add command to show version (#604)

* feat: add -version flag for jetkvm_app

* move code to kvm package

cmd/main.go

@@ -1,9 +1,27 @@
 package main
 
 import (
+	"flag"
+	"fmt"
+	"os"
+
 	"github.com/jetkvm/kvm"
 )
 
 func main() {
+	versionPtr := flag.Bool("version", false, "print version and exit")
+	versionJsonPtr := flag.Bool("version-json", false, "print version as json and exit")
+	flag.Parse()
+
+	if *versionPtr || *versionJsonPtr {
+		versionData, err := kvm.GetVersionData(*versionJsonPtr)
+		if err != nil {
+			fmt.Printf("failed to get version data: %v\n", err)
+			os.Exit(1)
+		}
+		fmt.Println(string(versionData))
+		return
+	}
+
 	kvm.Main()
 }