Add export option: use item.m_PathID vs item.UniqueID

[Shuraken007]

It's hard to match PathID and exported_file.

Example:

I'm trying to get exported follower by PathID 29140.
I'm going to assets.xml - exported list. Founded that asset has name Follower for this PathID.
I'm finding all exported files, starting on Follower with corresponding size to that asset, and got 9 files.
['Follower #1913', 'Follower #198519', 'Follower #198779', 'Follower #349', 'Follower #506', 'Follower #677', 'Follower #814', 'Follower #972', 'Follower']

So... case you'll use PathID vs UniqueID - I'll got only one file Follwer #29140.json
(It would be better - case the rule will always apply - even when file is not exists)

As I understand - corresponding function: Exporter.cs -> TryExportFile