Relax and rename auth policies for sender/receiver roles

Replaced SenderOrReceiverFullyAuth and ReceiverFullyAuth policies with more general SenderOrReceiver and Receiver policies. Updated policy definitions in AuthPolicy.cs to use nameof for clarity. Adjusted AddAuthorizationBuilder configuration and [Authorize] attributes in controllers to use the new, less restrictive policies, simplifying authorization logic.

EnvelopeGenerator.API/Controllers/TfaRegistrationController.cs

@@ -111,7 +111,7 @@ public class TfaRegistrationController : ControllerBase
     /// <summary>
     /// Logs out the envelope receiver from cookie authentication.
     /// </summary>
-    [Authorize(Policy = AuthPolicy.ReceiverFullyAuth)]
+    [Authorize(Policy = AuthPolicy.Receiver)]
     [HttpPost("auth/logout")]
     public async Task<IActionResult> LogOutAsync()
     {