feat: add sftp driver (close #1466)

drivers/sftp/meta.go

@@ -0,0 +1,30 @@
+package sftp
+
+import (
+	"github.com/alist-org/alist/v3/internal/driver"
+	"github.com/alist-org/alist/v3/internal/op"
+)
+
+type Addition struct {
+	Address    string `json:"address" required:"true"`
+	Username   string `json:"username" required:"true"`
+	PrivateKey string `json:"private_key" type:"text"`
+	Password   string `json:"password"`
+	driver.RootFolderPath
+}
+
+var config = driver.Config{
+	Name:        "SFTP",
+	LocalSort:   true,
+	OnlyLocal:   true,
+	DefaultRoot: "/",
+	CheckStatus: true,
+}
+
+func New() driver.Driver {
+	return &SFTP{}
+}
+
+func init() {
+	op.RegisterDriver(config, New)
+}