[Feat] (MG_Backend/DirectVulkan): wire glPolygonMode and glColorMaski into pipeline creation

Consume the polygon mode and per-draw-buffer color write masks that the
frontend already tracks, with runtime fallback for the device features
they require.

glPolygonMode:
- Add ConvertPolygonModeToVkEnum (GL_FILL/LINE/POINT -> VkPolygonMode).
- Thread a polygonMode field through PipelineCreatePayload, fold it into
  the pipeline cache hash (distinct modes need distinct pipelines), and
  apply it in PipelineFactory instead of the hardcoded VK_POLYGON_MODE_FILL.
- LINE/POINT require the fillModeNonSolid device feature: detect and
  enable it at device creation, cache m_fillModeNonSolidFeatureEnabled,
  and fall back to FILL at pipeline-build time when it is absent.

glColorMaski:
- The per-attachment color-blend loop now reads GetColorMaskIndexed(i)
  instead of the broadcast GetColorMask(), so each draw buffer gets its
  own write mask (already covered by the pipeline hash).
- Divergent per-attachment masks require independentBlend: cache
  m_independentBlendFeatureEnabled (was enabled but never recorded) and
  fall back to draw buffer 0's mask for every attachment when it is absent.

The internal depth-mipmap utility pipeline keeps VK_POLYGON_MODE_FILL (not
GL-driven). Library builds clean; full SanityTest sweep green (30/30).

MobileGL/MG_Backend/DirectVulkan/Renderer/PipelineFactory.h

@@ -29,6 +29,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
             VkSampleCountFlagBits rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;
             Uint32 subpass = 0;
             VkPrimitiveTopology topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
+            VkPolygonMode polygonMode = VK_POLYGON_MODE_FILL;
             VkCullModeFlags cullMode = VK_CULL_MODE_BACK_BIT;
             VkFrontFace frontFace = VK_FRONT_FACE_CLOCKWISE;
             Bool depthTestEnable = false;