Refactor ConfigDto class and update properties

- Change namespace to `EnvelopeGenerator.Application.DTOs`
- Remove `DocumentPath` property
- Update `SignatureHost` to be a required string

EnvelopeGenerator.Application/DTOs/ConfigDto.cs

@@ -8,11 +8,6 @@ namespace EnvelopeGenerator.Application.DTOs;
 [ApiExplorerSettings(IgnoreApi = true)]
 public class ConfigDto
 {
-    /// <summary>
-    /// Gets or sets the path to the document.
-    /// </summary>
-    public string? DocumentPath { get; set; }
-
     /// <summary>
     /// Gets or sets the sending profile identifier.
     /// </summary>
@@ -21,7 +16,7 @@ public class ConfigDto
     /// <summary>
     /// Gets or sets the signature host URL or name.
     /// </summary>
-    public string? SignatureHost { get; set; }
+    public required string SignatureHost { get; set; }
 
     /// <summary>
     /// Gets or sets the name of the external program.