Rename SystemDriver to WindowDriver and removed LinuxSystemDriver

Hopefully the last time I change my mind on what I want these to be
called. Reason behind this change is to minimize scope of a single
module. The WindowDriver should really only handle stuff related to
windows. If we need OS level functionality (e.g. get_os_name), that
should be the responsibility of the OS driver (or whatever that ends
being called). Remember, composition over inheritance.

engine/include/nova/platform/window_driver.h

@@ -0,0 +1,18 @@
+/**
+ * Copyright (c) 2025, Jayden Grubb <contact@jaydengrubb.com>
+ * 
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#pragma once
+
+#include <nova/api.h>
+
+namespace Nova {
+	class NOVA_API WindowDriver {
+	  public:
+		virtual ~WindowDriver() = default;
+
+		[[nodiscard]] virtual const char* get_surface_extension() const = 0;
+	};
+} // namespace Nova