More precise file locations

Fixes issue where it won't import on Windows 10 due to this: 
```VM75 renderer_init.js:73 Uncaught (in promise) Error: Error invoking remote method 'POWERCORD_COMPILE_MF_SASS': Error: Can't find stylesheet to import.
  ╷
1 │ @use 'modules';
  │ ^^^^^^^^^^^^^^```

src/_index.scss

@@ -1,9 +1,9 @@
-@use 'modules';
-@use 'titlebar';
-@use 'guilds';
-@use 'chat';
-@use 'friends';
-@use 'sidebars';
-@use 'flyouts';
-@use 'settings';
-@use 'fixations';
+@use '_modules.scss';
+@use '_titlebar.scss';
+@use '_guilds.scss';
+@use '_chat.scss';
+@use '_friends.scss';
+@use '_sidebars.scss';
+@use '_flyouts.scss';
+@use '_settings.scss';
+@use 'fixations';