Mark PSPDFKit-related code as obsolete

Added `[Obsolete]` attributes to classes, methods, and properties related to the deprecated PSPDFKit library and notifications.

- Marked `AnnotationHandler`, `DocStatusHandler`, `AnnotationBehavior`, and `DocStatusBehavior` as obsolete.
- Marked `Handle` methods in `DocStatusHandler` and `DocStatusBehavior` as obsolete.
- Marked `PsPdfKitAnnotation` property in `SignCommand` as obsolete.
- Marked `CreateOrUpdate` method in `AnnotationController` as obsolete.
- Added `Handle` methods in `DocStatusHandler` and `DocStatusBehavior` to send `CreateDocStatusCommand`.
- Updated `AnnotationController` dependencies to include `EnvelopeGenerator.Application.Common.Dto`.

These changes indicate a transition to `Signature.Commands.SignCommand` and deprecate PSPDFKit-related functionality.

EnvelopeGenerator.Application/Signature/Behaviors/AnnotationBehavior.cs

@@ -10,6 +10,7 @@ namespace EnvelopeGenerator.Application.Signature.Behaviors;
 /// Pipeline behavior that saves annotations.
 /// Executes first in the signing process.
 /// </summary>
+[Obsolete("This notification is deprecated. Use Signature.Commands.SignCommand instead.")]
 public class AnnotationBehavior : IPipelineBehavior<SignCommand, Unit>
 {
     private readonly IRepository<ElementAnnotation> _repo;

EnvelopeGenerator.Application/Signature/Behaviors/DocStatusBehavior.cs

@@ -33,6 +33,7 @@ public class DocStatusBehavior : IPipelineBehavior<SignCommand, Unit>
     /// <param name="next"></param>
     /// <param name="cancellationToken"></param>
     /// <returns></returns>
+    [Obsolete("This notification is deprecated. Use Signature.Commands.SignCommand instead.")]
     public async Task<Unit> Handle(SignCommand request, RequestHandlerDelegate<Unit> next, CancellationToken cancellationToken)
     {
         await _sender.Send(new CreateDocStatusCommand()

EnvelopeGenerator.Application/Signature/Commands/SignCommand.cs

@@ -19,6 +19,7 @@ public record SignCommand : IRequest
     /// <summary>
     /// The PSPDFKit annotation data.
     /// </summary>
+    [Obsolete("This notification is deprecated. Use Signature.Commands.SignCommand instead.")]
     public PsPdfKitAnnotation? PsPdfKitAnnotation { get; init; }
 
     /// <summary>