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/CMakeLists.txt

@@ -0,0 +1,35 @@
+cmake_minimum_required(VERSION 3.13)
+project(deps_src)
+
+# Include all dependency subdirectories
+
+# Header-only libraries (INTERFACE)
+add_subdirectory(agg)
+add_subdirectory(ankerl)
+add_subdirectory(fast_float)
+add_subdirectory(nanosvg)
+add_subdirectory(nlohmann)
+add_subdirectory(spline)      # Header-only spline library
+add_subdirectory(stb_dxt)     # Header-only STB DXT compression library
+
+# Static libraries
+add_subdirectory(Shiny)
+add_subdirectory(admesh)
+add_subdirectory(clipper)
+add_subdirectory(expat)
+add_subdirectory(glu-libtess)
+add_subdirectory(hidapi)
+add_subdirectory(hints)        # Hints library with utility executable
+add_subdirectory(imgui)
+add_subdirectory(imguizmo)
+add_subdirectory(libigl)
+add_subdirectory(libnest2d)
+add_subdirectory(mcut)
+add_subdirectory(miniz)
+add_subdirectory(minilzo)
+add_subdirectory(qhull)
+add_subdirectory(qoi)
+add_subdirectory(semver)      # Semver static library
+
+# Eigen header-only library
+add_subdirectory(eigen)