Add proprietary FontStyle enum

Removes dependency on Windows-only API from System.Drawing

VpSharp/src/FontStyle.cs

@@ -0,0 +1,22 @@
+namespace VpSharp;
+
+/// <summary>
+///     An enumeration of font styles.
+/// </summary>
+public enum FontStyle
+{
+    /// <summary>
+    ///     Regular font.
+    /// </summary>
+    Regular = 0,
+
+    /// <summary>
+    ///     Bold font.
+    /// </summary>
+    Bold = 1,
+
+    /// <summary>
+    ///     Italic font.
+    /// </summary>
+    Italic = 2
+}