feat: Add PACS.003.001.08 Builder and Integration Tests

- Implemented `Pacs00300108Builder` for constructing and serializing ISO 20022 pacs.003.001.08 messages (FI To FI Customer Direct Debit V08).
  - Added methods for setting group headers, adding direct debit transactions, and creating payment identification.
  - Included validation for required fields and transaction counting.
  - Supports XML generation and serialization capabilities.

- Updated `MessageBuilderFactory` to register the new `Pacs00300108Builder` for `MessageType.Pacs00300108`.

- Created integration tests for `Pacs00300108Builder` to ensure proper functionality and validation.
  - Tests include builder creation, basic message construction, required field validation, and transaction counting.

Author: cleilson pereira

Iso20022Library.Application/Builders/MessageBuilderFactory.cs

@@ -48,7 +48,8 @@ public class MessageBuilderFactory
         { MessageType.Pain00700107, () => new Pain00700107Builder() },
         { MessageType.Pain00700108, () => new Pain00700108Builder() },
         { MessageType.Pain00700109, () => new Pain00700109Builder() },
-        { MessageType.Pacs00200111, () => new Pacs.Pacs00200111Builder() }
+        { MessageType.Pacs00200111, () => new Pacs.Pacs00200111Builder() },
+        { MessageType.Pacs00300108, () => new Pacs.Pacs00300108Builder() }
     };
 
     /// <summary>