[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/RenderState/RenderState.h

@@ -94,6 +94,13 @@ namespace MobileGL {
         Unknown = -1
     };
 
+    enum class ProvokingVertexMode {
+        FirstVertex,
+        LastVertex,
+        ProvokingVertexModeCount,
+        Unknown = -1
+    };
+
     enum class CapabilityInput {
         Blend,
         ClipDistance0,
@@ -179,6 +186,7 @@ namespace MobileGL {
         Bool CullFaceEnabled = false;
         CullFaceMode CullFaceModeSetting = CullFaceMode::Back;
         FrontFaceMode FrontFaceModeSetting = FrontFaceMode::CounterClockwise;
+        ProvokingVertexMode ProvokingVertexModeSetting = ProvokingVertexMode::LastVertex;
 
         // Scissor
         Bool ScissorTestEnabled = false;
@@ -245,6 +253,8 @@ namespace MobileGL {
                 CullFaceMode GetCullFaceMode() const;
                 void SetFrontFaceMode(FrontFaceMode mode);
                 FrontFaceMode GetFrontFaceMode() const;
+                void SetProvokingVertexMode(ProvokingVertexMode mode);
+                ProvokingVertexMode GetProvokingVertexMode() const;
 
                 // Scissor
                 void SetScissorBox(IntVec4 box);      // x, y, width, height