Add columns to save item data before enhancement

[U-lis]

Currently, ItemEnhancements table only saves item level and exp after enhancement.
This makes hard to track item enhancement history.
Add PrevExp and PrevLevel columns and save data from state before enhancement.

[jaeho0103]

Migration desired start block
24.4 (ODIN) | 9893523
24.4 (HEIMDALL) | 1486892