fix(Interaction): set precise spring anchor

if attach mechanic is set to Spring Joint and snap type is set to
Precision Snap, set the anchor of the temporary SpringJoint to
controllerAttachPoint's current position in the grabbed object's space

Assets/SteamVR_Unity_Toolkit/Scripts/VRTK_InteractGrab.cs

@@ -168,6 +168,10 @@ private void CreateJoint(GameObject obj)
                 SpringJoint tempSpringJoint = obj.AddComponent<SpringJoint>();
                 tempSpringJoint.spring = objectScript.springJointStrength;
                 tempSpringJoint.damper = objectScript.springJointDamper;
+                if(objectScript.grabAttachMechanic == VRTK_InteractableObject.GrabSnapType.Precision_Snap)
+                {
+                    tempSpringJoint.anchor = obj.transform.InverseTransformPoint(controllerAttachPoint.position);
+                }
                 controllerAttachJoint = tempSpringJoint;
             }
             controllerAttachJoint.breakForce = objectScript.detachThreshold;
@@ -408,4 +412,4 @@ private void Update()
             }
         }
     }
-}
+}