Refactor `driver.NewDriver`

`driver.NewDriver` used to construct a govnomi client on its own while
the same work can be done by calling `govmomi.NewClient`.

driver/driver.go

@@ -9,8 +9,6 @@ import (
 	"github.com/vmware/govmomi/object"
 	"time"
 	"github.com/vmware/govmomi/session"
-	"github.com/vmware/govmomi/vim25/soap"
-	"github.com/vmware/govmomi/vim25"
 )
 
 type Driver struct {
@@ -35,25 +33,13 @@ func NewDriver(config *ConnectConfig) (*Driver, error) {
 	if err != nil {
 		return nil, err
 	}
-	credentials := url.UserPassword(config.Username, config.Password)
-	vcenter_url.User = credentials
+	vcenter_url.User = url.UserPassword(config.Username, config.Password)
 
-	soapClient := soap.NewClient(vcenter_url, config.InsecureConnection)
-	vimClient, err := vim25.NewClient(ctx, soapClient)
-	if err != nil {
-		return nil, err
-	}
-
-	vimClient.RoundTripper = session.KeepAlive(vimClient.RoundTripper, 10*time.Minute)
-	client := &govmomi.Client{
-		Client:         vimClient,
-		SessionManager: session.NewManager(vimClient),
-	}
-
-	err = client.SessionManager.Login(ctx, credentials)
+	client, err := govmomi.NewClient(ctx, vcenter_url, config.InsecureConnection)
 	if err != nil {
 		return nil, err
 	}
+	client.RoundTripper = session.KeepAlive(client.RoundTripper, 10*time.Minute)
 
 	finder := find.NewFinder(client.Client, false)
 	datacenter, err := finder.DatacenterOrDefault(ctx, config.Datacenter)