Disable GL_KHR_cooperative_matrix Vulkan extension if not available. (#11117)

* Disable GL_KHR_cooperative_matrix Vulkan extension if not available.

* Perform Vulkan extensions checks in a more sensible order

* Remove unnecessary #ifdef directive

ggml/src/ggml-vulkan/vulkan-shaders/test_coopmat_support.comp

@@ -0,0 +1,7 @@
+#version 460
+
+#extension GL_KHR_cooperative_matrix : require
+
+void main()
+{
+}