[Feat] (MG_Backend): wire primitive restart into both backends; detect dualSrcBlend

Make GL_PRIMITIVE_RESTART[_FIXED_INDEX] actually take effect at draw time,
following the detect-at-init / POST / fallback-or-hard-fail discipline.

DirectVulkan:
- Thread primitiveRestartEnable through the pipeline (payload + hash +
  input-assembly), set from the GL_PRIMITIVE_RESTART / _FIXED_INDEX caps.
- Detect and enable primitiveTopologyListRestart
  (VK_EXT_primitive_topology_list_restart) at device creation; cache it.
  Strip/fan restart needs no feature; a *list* topology with restart and
  no feature hard-fails at the draw with the reason.
- Vulkan only restarts on the fixed all-ones index value, so an arbitrary
  GL_PRIMITIVE_RESTART index that is not that value hard-fails in
  UploadAndBindIndexBuffer (where the index type is known).
- Also detect+enable and cache the dualSrcBlend base feature (groundwork
  for GL_SRC1_* dual-source blending).

DirectGLES:
- Sync GL_PRIMITIVE_RESTART_FIXED_INDEX from either restart cap (GLES core
  has only the fixed-index form); an arbitrary non-fixed index hard-fails
  in the indexed draw paths with the reason.

POST: dualSrcBlend and primitiveTopologyListRestart capability rows (Pass
when supported, Warn with the fallback/hard-fail consequence otherwise).

Library builds clean; SanityTest 31/31. (The actual restart rendering and
the hard-fail paths need a real GPU and are not runtime-testable here.)

MobileGL/MG_Backend/DirectVulkan/Renderer/VulkanRenderer.h

@@ -354,6 +354,11 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         // drive a runtime fallback when the device lacks them.
         Bool m_fillModeNonSolidFeatureEnabled = false;
         Bool m_independentBlendFeatureEnabled = false;
+        // dualSrcBlend gates GL_SRC1_* blend factors (glBindFragDataLocationIndexed dual-source blend);
+        // primitiveTopologyListRestart gates primitive restart on *list* topologies (strip/fan restart
+        // needs no feature). Both cached at device creation and drive a hard-fail-at-draw when absent.
+        Bool m_dualSrcBlendFeatureEnabled = false;
+        Bool m_primitiveTopologyListRestartFeatureEnabled = false;
         // Cached at device creation from the graphics queue family properties
         // and device limits; drives timer-query support.
         Uint32 m_timestampValidBits = 0;