[Fix] (MG_Backend/DirectVulkan): support Voxy rendering

Implemented:

- Advertise Voxy-required DirectVulkan extensions without raising the reported OpenGL version.

- Add DirectVulkan compute, indirect draw count, DSA, readback, and buffer state paths needed by Voxy.

Fixed:

- Enable Vulkan shaderInt64 and drawIndirectFirstInstance so Voxy baseInstance-driven LOD draws address the correct section data.

- Fix DirectVulkan synchronization, framebuffer, texture readback, and shader interface handling used by Voxy and Minecraft screenshots.

Tests:

- Add MG_Test coverage for DirectVulkan extension advertising, DSA buffer/texture/framebuffer/vertex-array behavior, persistent mapped readback, and shader/program paths.

MobileGL/MG_State/GLState/Core.cpp

@@ -413,6 +413,14 @@ namespace MobileGL::MG_State {
             return m_renderState.GetFrontFaceMode();
         }
 
+        void GLContext::SetProvokingVertexMode(ProvokingVertexMode mode) {
+            m_renderState.SetProvokingVertexMode(mode);
+        }
+
+        ProvokingVertexMode GLContext::GetProvokingVertexMode() const {
+            return m_renderState.GetProvokingVertexMode();
+        }
+
         void GLContext::SetScissorBox(IntVec4 box) {
             m_renderState.SetScissorBox(box);
         }