Expose RWMesh

[andrew-gropyus]

RWMesh classes do not appear to be included in cadquery-ocp, although methods that return RWMesh instances exist.

For example:

from OCP.RWGltf import RWGltf_CafWriter
from OCP.TCollection import TCollection_AsciiString

output_path_str = TCollection_AsciiString("output.glb")
writer = RWGltf_CafWriter(output_path_str, True)
writer.ChangeCoordinateSystemConverter().SetOutputLengthUnit(0.001)

errors with:

TypeError: Unregistered type : RWMesh_CoordinateSystemConverter

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "main.py", line 6, in <module>
    writer.ChangeCoordinateSystemConverter().SetOutputLengthUnit(0.001)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: Unable to convert function return value to a Python type! The signature was
	(self: OCP.OCP.RWGltf.RWGltf_CafWriter) -> RWMesh_CoordinateSystemConverter