Fix kernel/mapping plugin output dir and IfcViewer link dependencies

Use $<TARGET_FILE_DIR:IfcGeom> instead of hardcoded
${CMAKE_BINARY_DIR}/ifcgeom/$<CONFIG> for plugin runtime dirs — the
old path was wrong on non-MSVC generators where $<CONFIG> expands
empty. Add explicit add_dependencies for kernel/mapping plugins so
IfcViewer waits for them to build, and drop the redundant direct link
against ${kernel_libraries}.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/ifcgeom/mapping/CMakeLists.txt

@@ -1,6 +1,6 @@
 find_package(Eigen3 REQUIRED)
 
-set(mapping_plugin_runtime_dir "${CMAKE_BINARY_DIR}/ifcgeom/$<CONFIG>")
+set(mapping_plugin_runtime_dir "$<TARGET_FILE_DIR:IfcGeom>")
 
 foreach(schema ${SCHEMA_VERSIONS})
     file(GLOB IFCGEOM_I_FILES *.i)