ksys/res: Implement EntryFactory (base class and template)

Also adds a heap-related function that's used by EntryFactory
(and many other functions)

src/KingSystem/Resource/resEntryFactory.cpp

@@ -0,0 +1,20 @@
+#include "KingSystem/Resource/resEntryFactory.h"
+
+namespace ksys::res {
+
+static EntryFactory<Resource> sDefaultEntryFactory;
+
+u32 EntryFactoryBase::getResourceSize() const {
+    KSYS_CHECK_SIZE_NX150(sead::DirectResource, 0x20);
+    return sizeof(sead::DirectResource);
+}
+
+u32 EntryFactoryBase::getLoadDataAlignment() const {
+    return sizeof(void*);
+}
+
+EntryFactory<Resource>& getDefaultResourceFactory() {
+    return sDefaultEntryFactory;
+}
+
+}  // namespace ksys::res