Rename snake_case Class names (Remaining Bits) (#19237)

* Rename snake_case Class names

* Clang format

* Fix build issues

src/openrct2-ui/windows/Main.cpp

@@ -71,7 +71,7 @@ private:
  * Creates the main window that holds the main viewport.
  *  rct2: 0x0066B3E8
  */
-rct_window* WindowMainOpen()
+WindowBase* WindowMainOpen()
 {
     return WindowCreate<MainWindow>(WindowClass::MainWindow, { 0, 0 }, ContextGetWidth(), ContextGetHeight(), WF_STICK_TO_BACK);
 }