Editor toling to easier create data assets

Source/ProjectEleriEditor/Private/Eleri/EleriAssetCategory.h

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+// Fill out your copyright notice in the Description page of Project Settings.
+
+#pragma once
+
+#include "CoreMinimal.h"
+#include "Misc/AssetCategoryPath.h"
+
+/**
+ * The one category every data asset type of this project is filed under in the Content Browser.
+ *
+ * A category is a path rather than an enum entry: the asset definition a data asset type is described by
+ * hands this path to the engine, the engine derives the key it groups by from the path's source string,
+ * and both the Filters panel and the Add menu read that same list. Registering it with the Asset Tools
+ * as well is only what the older Content Browser style needs, which still files the Add menu by the
+ * EAssetTypeCategories bitmask instead of by the path.
+ */
+namespace EleriAssetCategory
+{
+	/** The shared category path. The reference is to a function-local static, so it is safe to copy from
+	 *  a definition's initialiser, but it must not be held on to once the module has been shut down. */
+	const FAssetCategoryPath& Get();
+
+	/** The EAssetTypeCategories bit for this category, for UFactory::GetMenuCategories(). Registered on
+	 *  the first call and the same value on every call after it. */
+	uint32 GetLegacyCategoryBit();
+}