Kernel: Move VMObject::for_each_region() to MemoryManager.h

It can't be in VMObject.h since it depends on MemoryManager.h

Kernel/VM/InodeVMObject.cpp

@@ -102,18 +102,3 @@ void InodeVMObject::inode_contents_changed(Badge<Inode>, off_t offset, ssize_t s
         region.remap();
     });
 }
-
-template<typename Callback>
-void VMObject::for_each_region(Callback callback)
-{
-    // FIXME: Figure out a better data structure so we don't have to walk every single region every time an inode changes.
-    //        Perhaps VMObject could have a Vector<Region*> with all of his mappers?
-    for (auto& region : MM.m_user_regions) {
-        if (&region.vmobject() == this)
-            callback(region);
-    }
-    for (auto& region : MM.m_kernel_regions) {
-        if (&region.vmobject() == this)
-            callback(region);
-    }
-}