[DarkMode] Dark mode on Progress and Find in finder dialogs

Notepad++ v8.1.2 does not apply dark mode on on Progress and Find in finder dialogs.

![image](https://user-images.githubusercontent.com/55940305/126868867-96edb6a3-4848-4b47-8155-7e1c5764b5c6.png)

part of https://github.com/notepad-plus-plus/notepad-plus-plus/issues/10171
