Refactor folder (#10475)

Move many third-party components' source codes from the src folder to a new folder called deps_src. The goal is to make the code structure clearer and easier to navigate.

deps_src/spline/CMakeLists.txt

@@ -0,0 +1,37 @@
+cmake_minimum_required(VERSION 3.13)
+project(spline)
+
+# Create interface library for spline (header-only library)
+add_library(spline INTERFACE)
+
+# Set include directories for the interface library
+target_include_directories(spline 
+    INTERFACE 
+        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+        $<INSTALL_INTERFACE:include>
+)
+
+# Add compile features
+target_compile_features(spline INTERFACE cxx_std_11)
+
+# Create an alias for consistent naming
+add_library(spline::spline ALIAS spline)
+
+# Install headers if needed
+install(FILES 
+    spline.h
+    DESTINATION include/spline
+)
+
+# Install the interface library
+install(TARGETS spline
+    EXPORT splineTargets
+    INCLUDES DESTINATION include
+)
+
+# Export the targets
+install(EXPORT splineTargets
+    FILE splineTargets.cmake
+    NAMESPACE spline::
+    DESTINATION lib/cmake/spline
+)