Match files not only by name, but by their position within the tree for course copy

For course copy we find candidates to be the same file based on name and size (depending on the LMS). We could also try to mach the position on the folder structure.

### Canvas

We don't support folder here yet.

### Blackboard

We do support folders but the API also gets us size, which makes false positives less likely

### D2L

The API doesn't gives us size so we only compare name here. The issue is not as likely to happen as depending on the storage options D2L doesn't allow names to be the same.