Update the api for serving plugins and provide a utility to pass TLS data for commuinicating with the vault process

plugins/database/postgresql/postgresql-database-plugin/main.go

@@ -4,11 +4,16 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/hashicorp/vault/helper/pluginutil"
 	"github.com/hashicorp/vault/plugins/database/postgresql"
 )
 
 func main() {
-	err := postgresql.Run()
+	apiClientMeta := &pluginutil.APIClientMeta{}
+	flags := apiClientMeta.FlagSet()
+	flags.Parse(os.Args)
+
+	err := postgresql.Run(apiClientMeta.GetTLSConfig())
 	if err != nil {
 		fmt.Println(err)
 		os.Exit(1)