LibGL: Turn Sampler2D into an actual class

This extracts the sampler functionality into its own class.
Beginning with OpenGL 3 samplers are actual objects, separate
from textures. It makes sense to do this already as it also
cleans up code organization quite a bit.

Userland/Libraries/LibGL/Tex/MipMap.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
+ * Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Vector.h>
+#include <LibGL/GL/gl.h>
+#include <LibGfx/Vector4.h>
+
+namespace GL {
+
+class MipMap {
+public:
+    MipMap() = default;
+    ~MipMap() = default;
+
+    void set_width(GLsizei width) { m_width = width; }
+    void set_height(GLsizei height) { m_height = height; }
+    GLsizei width() const { return m_width; }
+    GLsizei height() const { return m_height; }
+
+    Vector<u32>& pixel_data() { return m_pixel_data; }
+    const Vector<u32>& pixel_data() const { return m_pixel_data; }
+
+    FloatVector4 texel(unsigned x, unsigned y) const
+    {
+        if (x >= (unsigned)m_width || y >= (unsigned)m_height)
+            return { 0, 0, 0, 0 };
+
+        u32 texel = m_pixel_data.at(y * m_width + x);
+
+        return {
+            (texel & 0xff) / 255.f,
+            ((texel >> 8) & 0xff) / 255.f,
+            ((texel >> 16) & 0xff) / 255.f,
+            ((texel >> 24) & 0xff) / 255.f
+        };
+    }
+
+private:
+    GLsizei m_width;
+    GLsizei m_height;
+    Vector<u32> m_pixel_data;
+};
+}