feat(gx): add const getter for top of matrix stack

src/gx/CGxMatrixStack.cpp

@@ -28,3 +28,7 @@ C44Matrix& CGxMatrixStack::Top() {
     this->m_flags[this->m_level] &= 0xFFFFFFFE;
     return this->m_mtx[this->m_level];
 }
+
+const C44Matrix& CGxMatrixStack::TopConst() {
+    return this->m_mtx[this->m_level];
+}

src/gx/CGxMatrixStack.hpp

@@ -17,6 +17,7 @@ class CGxMatrixStack {
         void Pop(void);
         void Push(void);
         C44Matrix& Top(void);
+        const C44Matrix& TopConst();
 };
 
 #endif