Simplify AttachedInfo, FileLocations in particular

• MOST of the times (for read def) we use just INFO and we don't need subItems tree or whatever
•   QMap<Path, Ptr> m_subItems;  ← Typically only subpart of the Path, like "[""]" or ".objects" or smth else. maybe it's actually PathComponent-s 
• Looks like foundTreePath and rootTreePath could be removed..... 
• Remove ensureItemAtPath ?? same as infoAtPath ? Which I assume thought to be static at some point?

Why AttachedInfo and FileLocations must be aligned hierarchicaly with the Path hiearachy? Like When looking for a AttachedInfo<FileLocation> it's not just map Path - Info, it's tress, where each Node has Subitems etc. Like whatever we modify we are structurally(a.k.a. Path defined) valid?

What we need in most cases just a simple hash map <Path - FileLocations> ?{}