Added a password rule engine

Bitvault/DiversityBonusRule.cs

@@ -0,0 +1,29 @@
+using System.Text.RegularExpressions;
+
+namespace Bitvault;
+
+public partial class DiversityBonusRule : 
+    IPasswordRule
+{
+    public int CalculateScore(string password)
+    {
+        bool hasUppercase = UppercaseRegex().IsMatch(password);
+        bool hasLowercase = LowercaseRegex().IsMatch(password);
+        bool hasDigit = DigitRegex().IsMatch(password);
+        bool hasSpecialChar = SpecialCharRegex().IsMatch(password);
+
+        return (hasUppercase && hasLowercase && hasDigit && hasSpecialChar) ? 2 : 0;
+    }
+
+    [GeneratedRegex(@"[A-Z]")]
+    private static partial Regex UppercaseRegex();
+
+    [GeneratedRegex(@"[a-z]")]
+    private static partial Regex LowercaseRegex();
+
+    [GeneratedRegex(@"\d")]
+    private static partial Regex DigitRegex();
+
+    [GeneratedRegex(@"[^a-zA-Z0-9]")]
+    private static partial Regex SpecialCharRegex();
+}