backend/tardigrade: Set UserAgent to rclone

This provides two things:

* It gives Storj insight into which uplink clients are using the
  network.
* It facilitate rclone participating in the Tardigrade Open Source
  Partner Program https://tardigrade.io/partner/

backend/tardigrade/fs.go

@@ -269,7 +269,9 @@ func (f *Fs) connect(ctx context.Context) (project *uplink.Project, err error) {
 	fs.Debugf(f, "connecting...")
 	defer fs.Debugf(f, "connected: %+v", err)
 
-	cfg := uplink.Config{}
+	cfg := uplink.Config{
+		UserAgent: "rclone",
+	}
 
 	project, err = cfg.OpenProject(ctx, f.access)
 	if err != nil {