Allow user to specify tolerance for locate

[Darylgolden]

It would be helpful if the user can specify the tolerance for whether a slightly offset point would be considered on the curve.

[dhermes]

Relevant lines to make this happen:

• bezier/src/python/bezier/hazmat/curve_helpers.py

  Line 894 in e6925aa

  if np.std(params) > _LOCATE_STD_CAP:

• bezier/src/python/bezier/hazmat/curve_helpers.py

  Line 883 in e6925aa

  if _py_helpers.contains_nd(candidate, point.ravel(order="F")):

  (would need to add a buffer)

• bezier/src/fortran/curve.f90

  Line 547 in e6925aa

  if (std_dev > LOCATE_STD_CAP) then