Add support for `key` to be `Index` in `Series.locate(key)`

[stress-tess]

Related to a question from #1477, should we add the ability for key to be an Index in Series.locate? It should be a simple fix if we want it, i believe all that's required is

def locate(self, key: Union[int, pdarray, Index, Series, List, Tuple]) -> Series:
  ...
  elif isinstance(key, Index):
    idx = self.index.lookup(key.index)
  ...

but we should make sure to test single and multi index to verify correct functionality