LibGfx: Prepare the paint code for fonts whose glyphs are color bitmaps

This patch does three things:
- Font::has_color_bitmaps() (true if CBLC and CBDT are present)
- Glyph now knows when its bitmap comes from a color bitmap font
- Painter draws color bitmap glyphs with the appropriate scaling etc

Userland/Libraries/LibGfx/Font/BitmapFont.h

@@ -137,6 +137,8 @@ private:
 
     void update_x_height() { m_x_height = m_baseline - m_mean_line; };
 
+    virtual bool has_color_bitmaps() const override { return false; }
+
     DeprecatedString m_name;
     DeprecatedString m_family;
     size_t m_glyph_count { 0 };