Refactor Star Wars Journal module structure and styles

- Replaced `main.js` with `asc-starwars.js` and modularized journal sheet logic into `journalSheets.js`.
- Updated `module.json` to use ES modules and adjusted script/style references accordingly.
- Consolidated and enhanced CSS styles into `asc-starwars-journal.css` and added `asc-ffg-starwars.css`.
- Removed deprecated `starwars-journal.css` and outdated journal sheet registration logic.

src/scripts/journalSheets.js

@@ -0,0 +1,7 @@
+export class StarWarsStyleJournalSheet extends JournalSheet {
+  static get defaultOptions() {
+    return mergeObject(super.defaultOptions, {
+      classes: [...(super.defaultOptions.classes || []), 'asc-starwars-customsheet'],
+    });
+  }
+}