Fix hasStaticShape() method on vectors and tensors to work correctly for...

Fix hasStaticShape() method on vectors and tensors to work correctly for unranked tensors and remove getShape() method for unranked tensors.

Unranked tensors used to return an empty list of dimensions as their shape. This is confusing since an empty list of dimensions is also returned for 0-D tensors. In particular, hasStaticShape() method used to check if any of the dimensions are -1, which held for unranked tensors even though they don't have static shape.

PiperOrigin-RevId: 221571138