BLI: move CPPType to blenlib

For more detail about `CPPType`, see `BLI_cpp_type.hh` and D14367.

Differential Revision: https://developer.blender.org/D14367

source/blender/functions/FN_multi_function.hh

@@ -154,7 +154,6 @@ inline MFParamsBuilder::MFParamsBuilder(const MultiFunction &fn, const IndexMask
 }
 
 namespace multi_function_types {
-using fn::CPPType;
 using fn::GMutableSpan;
 using fn::GSpan;
 using fn::MFContext;