Add PKCS#11-based PDF signing infrastructure

Introduced a cryptographic infrastructure for PDF signing and validation using PKCS#11-based hardware security modules (HSMs) or software tokens. Key changes include:

- Added `PdfDigitalSignatureService` for signing PDFs, multi-signature support, and signature validation.
- Implemented `Pkcs11ExternalSigner` and `Pkcs11PdfSigningRsa` for PKCS#11-based signing with DevExpress PDF infrastructure.
- Added utilities like `Pkcs11SessionRunner`, `Pkcs11InteropBootstrap`, and `Pkcs11ToolBridge` for session management, library initialization, and fallback mechanisms.
- Introduced `Pkcs11Options` for managing PKCS#11 configurations.
- Updated project dependencies to include `DevExpress.Document.Processor`, `System.Security.Cryptography.Pkcs`, and `Pkcs11Interop`.
- Enhanced error handling and fallback support for PKCS#11 operations.

These changes enable robust and extensible PDF signing capabilities with detailed signature metadata extraction and validation.

EnvelopeGenerator.Infrastructure.Crypt/Services/Pkcs11DigestInfoBuilder.cs

@@ -0,0 +1,43 @@
+using System.Security.Cryptography;
+
+namespace EnvelopeGenerator.Infrastructure.Crypt.Services;
+
+internal static class Pkcs11DigestInfoBuilder
+{
+    public static byte[] Build(byte[] hash, HashAlgorithmName hashAlgorithm)
+    {
+        byte[] prefix = hashAlgorithm.Name switch
+        {
+            "SHA256" =>
+            [
+                0x30, 0x31,
+                0x30, 0x0d,
+                0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
+                0x05, 0x00,
+                0x04, 0x20
+            ],
+            "SHA384" =>
+            [
+                0x30, 0x41,
+                0x30, 0x0d,
+                0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
+                0x05, 0x00,
+                0x04, 0x30
+            ],
+            "SHA512" =>
+            [
+                0x30, 0x51,
+                0x30, 0x0d,
+                0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
+                0x05, 0x00,
+                0x04, 0x40
+            ],
+            _ => throw new NotSupportedException($"Hash algorithm '{hashAlgorithm.Name}' is not supported.")
+        };
+
+        var digestInfo = new byte[prefix.Length + hash.Length];
+        Buffer.BlockCopy(prefix, 0, digestInfo, 0, prefix.Length);
+        Buffer.BlockCopy(hash, 0, digestInfo, prefix.Length, hash.Length);
+        return digestInfo;
+    }
+}