layers: Kill SET_NODE construct and just use DescriptorSet class
Migrated setMap to just use DescriptorSet class natively. SET_NODE was
just wrapping that class but that's not necessary so killing extra indirection.
diff --git a/layers/descriptor_sets.h b/layers/descriptor_sets.h
index fb08e3d..1cce047 100644
--- a/layers/descriptor_sets.h
+++ b/layers/descriptor_sets.h
@@ -273,7 +273,7 @@
* those maps is performed externally. The set class relies on their contents to
* be correct at the time of update.
*/
-class DescriptorSet {
+class DescriptorSet : public BASE_NODE {
public:
DescriptorSet(const VkDescriptorSet, const DescriptorSetLayout *, const std::unordered_map<VkBuffer, BUFFER_NODE> *,
const std::unordered_map<VkDeviceMemory, DEVICE_MEM_INFO> *,