file_sys: Support load game collection (#6582)

Adds support for loading games with multiple programs embedded within such as the Dragon Quest 1+2+3 Collection

src/core/loader/loader.h

@@ -226,6 +226,17 @@ public:
         return ResultStatus::ErrorNotImplemented;
     }
 
+    /**
+     * Get the program ids of the application
+     *
+     * @param[out] out_program_ids Reference to store program ids into
+     *
+     * @return ResultStatus result of function
+     */
+    virtual ResultStatus ReadProgramIds(std::vector<u64>& out_program_ids) {
+        return ResultStatus::ErrorNotImplemented;
+    }
+
     /**
      * Get the RomFS of the application
      * Since the RomFS can be huge, we return a file reference instead of copying to a buffer
@@ -324,6 +335,6 @@ protected:
  * @return the best loader for this file.
  */
 std::unique_ptr<AppLoader> GetLoader(Core::System& system, FileSys::VirtualFile file,
-                                     std::size_t program_index = 0);
+                                     u64 program_id = 0, std::size_t program_index = 0);
 
 } // namespace Loader