[Feature Request] copy sample files in Hitsound Copier

[cihe13375]

Prerequisites

• [x] I have checked the Trello and confirmed that the feature is not already planned

Description

Add an option in Hitsound Copier to copy sample files (.wav), if the source and destination belongs to different mapsets.

Motivation

I usually put the hitsound diff in a separate mapset (so it won't be uploaded when updating the main mapset), which means with the current behavior, I have to manually copy the sample files after adding/editing them. It would be more convenient if Hitsound Copier can copy them automatically.