expose add font family method

In order to add custom font that loaded locally in the project, it's essential to insert the font name into the exisiting fonts dictionary.
thus I exposed the insert method to the PdfGenerator class

Author: Omer

Source/HtmlRenderer.PdfSharp.Core/Adapters/PdfSharpAdapter.cs

@@ -127,8 +127,10 @@ protected override RFont CreateFontInt(string family, double size, RFontStyle st
         protected override RFont CreateFontInt(RFontFamily family, double size, RFontStyle style)
         {
             var fontStyle = (XFontStyle)((int)style);
-            var xFont = new XFont(((FontFamilyAdapter)family).FontFamily.Name, size, fontStyle, new XPdfFontOptions(PdfFontEncoding.Unicode));
+            string fontName = family is FontFamilyAdapter adapter ? adapter.FontFamily.Name : family.Name;
+            var xFont = new XFont(fontName, size, fontStyle, new XPdfFontOptions(PdfFontEncoding.Unicode));
             return new FontAdapter(xFont);
         }
+
     }
 }

Source/HtmlRenderer.PdfSharp.Core/PdfGenerator.cs

@@ -14,6 +14,7 @@
 using PdfSharpCore.Drawing;
 using PdfSharpCore.Pdf;
 using System;
+using TheArtOfDev.HtmlRenderer.Adapters;
 using TheArtOfDev.HtmlRenderer.Core;
 using TheArtOfDev.HtmlRenderer.Core.Entities;
 using TheArtOfDev.HtmlRenderer.Core.Utils;
@@ -44,6 +45,11 @@ public static void AddFontFamilyMapping(string fromFamily, string toFamily)
             PdfSharpAdapter.Instance.AddFontFamilyMapping(fromFamily, toFamily);
         }
 
+        public static void AddFontFamily(RFontFamily fontFamily)
+        {
+            PdfSharpAdapter.Instance.AddFontFamily(fontFamily);
+        }
+
         /// <summary>
         /// Parse the given stylesheet to <see cref="CssData"/> object.<br/>
         /// If <paramref name="combineWithDefault"/> is true the parsed css blocks are added to the