Rename GetDocumentAsync to GetDocumentOfReceiverAsync

Updated the method name in EnvelopeReceiverPageDataService
to clarify its purpose of retrieving documents for a receiver.
Refactored all references in Razor pages (ReceiverPage.razor,
ReceiverSignedPage.razor, EnvelopeReceiverPage.razor) to use
the new method name. No changes were made to the method's
logic or functionality. This improves code clarity and consistency.

EnvelopeGenerator.Server/EnvelopeGenerator.Server/Services/EnvelopeReceiverPageDataService.cs

@@ -31,7 +31,7 @@ public class EnvelopeReceiverPageDataService(
     /// <summary>
     /// Loads the PDF document bytes for the authenticated receiver.
     /// </summary>
-    public async Task<byte[]?> GetDocumentAsync(ClaimsPrincipal user, CancellationToken cancellationToken = default)
+    public async Task<byte[]?> GetDocumentOfReceiverAsync(ClaimsPrincipal user, CancellationToken cancellationToken = default)
     {
         var document = await mediator.Send(new ReadDocumentQuery(EnvelopeId: user.EnvelopeId()), cancellationToken);
         return document.ByteData;