Clean and update dragonbones sample

The dragonbones sample has too many commented code, it's hard to read.
Also the `Button` there should be changed to the `TextButton` from korge.
Scenes should probably be divided into several files to make them clearer and easier to read.

Start by locating the dragonbones sample entry point and its scene files, then review the current commented code and Button usage. The work is done when unnecessary comments are removed, Button is replaced with KorGE's TextButton, and scenes are divided into clearer files without changing the sample's behavior.

Written by the indexing model from the issue text.