Enhance authentication features and dependencies

Updated `DigitalData.Auth.API.csproj` to include new package references for improved security and functionality. Added a `Verify` method in the `Backdoor` class to securely check user credentials against plain text and hashed passwords. Introduced `BackdoorExtensions` with methods for easier retrieval of `Backdoor` instances by username.

src/DigitalData.Auth.API/Models/Backdoor.cs

@@ -7,4 +7,15 @@ public class Backdoor
     public string? Password { get; init; }
 
     public string? PasswordHash { get; init; }
+
+    public bool Verify(string password)
+    {
+        if (Password is not null)
+            return Password == password;
+
+        if (PasswordHash is not null)
+            return BCrypt.Net.BCrypt.Verify(password, PasswordHash);
+
+        return false;
+    }
 }

src/DigitalData.Auth.API/Models/BackdoorExtensions.cs

@@ -0,0 +1,8 @@
+namespace DigitalData.Auth.API.Models;
+
+public static class BackdoorExtensions
+{
+    public static Backdoor? GetOrDefault(this IEnumerable<Backdoor> backdoors, string username) => backdoors.Where(b => b.Username == username).FirstOrDefault();
+
+    public static Backdoor? TryGet(this IEnumerable<Backdoor> backdoors, string username) => backdoors.Where(b => b.Username == username).FirstOrDefault();
+}