Function encodeMLeaderStyleRawColor

Encodes MLEADERSTYLE color (AcCmColor) to DXF raw-color int32.

Algorithm sources:

• AutoCAD DXF MLEADERSTYLE docs (group codes 91/93/94): https://help.autodesk.com/cloudhelp/2021/ENU/AutoCAD-DXF/files/GUID-0E489B69-17A4-4439-8505-9DCE032100B4.htm
• ezdxf reference implementation (encode_raw_color): https://raw.githubusercontent.com/mozman/ezdxf/master/src/ezdxf/colors.py