Standardize randomPolygon and randomLineString options from snake_case to camelCase

[mfedderly]

#2896 noticed that these options did not follow the standard of camelCase across the rest of the library. In v8 we can quickly change these to be consistent with the rest of the packages.

randomPolygon:
  num_vertices -> numVertices
  max_radial_length -> maxRadialLength
randomLineString
  num_vertices -> numVertices
  max_length -> maxLength
  max_rotation -> maxRotation