[CMake] remove traces of assembly module

the assembly module was removed for FC 0.20 but it appears still in CMake as build option.

This PR tries to remove the remaining traces (maybe more needs to be done?)

cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake

@@ -111,7 +111,6 @@ macro(InitializeFreeCADBuildOptions)
     option(BUILD_TEMPLATE "Build the FreeCAD template module which is only for testing purposes" OFF)
     option(BUILD_ADDONMGR "Build the FreeCAD addon manager module" ON)
     option(BUILD_ARCH "Build the FreeCAD Architecture module" ON)
-    option(BUILD_ASSEMBLY "Build the FreeCAD Assembly module" OFF)
     option(BUILD_COMPLETE "Build the FreeCAD complete module" OFF)
     option(BUILD_DRAFT "Build the FreeCAD draft module" ON)
     option(BUILD_DRAWING "Build the FreeCAD drawing module" ON)

src/Mod/Import/App/CMakeLists.txt

@@ -18,7 +18,6 @@ link_directories(${OCC_LIBRARY_DIR})
 
 set(Import_LIBS
     Part
-    #Assembly
     ${OCC_OCAF_LIBRARIES}
     ${OCC_OCAF_DEBUG_LIBRARIES}
 )