LibGL+LibSoftGPU: Add method to query device info

This adds a method `info()` to SoftGPU that returns the name of the
hardware vendor and device name, as well as the number of texture untis.

LibGL uses the returned texture unit count to initialize its internal
texture unit array.

Userland/Libraries/LibSoftGPU/DeviceInfo.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/String.h>
+
+namespace SoftGPU {
+
+struct DeviceInfo final {
+    String vendor_name;
+    String device_name;
+    unsigned num_texture_units;
+};
+
+}