Refactor envelope and receiver response models

- Updated `ReadEnvelopeReceiverResponse` to use `ReadEnvelopeResponse` instead of `ReadReceiverResponse`.
- Modified `ReadReceiverResponse` to include additional parameters in its constructor for better detail.
- Introduced a new `ReadEnvelopeResponse` record with comprehensive properties and a computed `StatusName`.

EnvelopeGenerator.Application/Receivers/Queries/Read/ReadReceiverResponse.cs

@@ -1,5 +1,5 @@
 namespace EnvelopeGenerator.Application.Receivers.Queries.Read;
 
-public record ReadReceiverResponse
+public record ReadReceiverResponse(int Id, string EmailAddress, DateTime AddedWhen, string Signature)
 {
 }