refactored connection classes to be more generic and accept credentials of different apps.

backend/src/main/java/com/vaessl/app/dto/ConnectionRequest.java

@@ -1,9 +1,13 @@
 package com.vaessl.app.dto;
 
+import java.util.Map;
+
 import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotEmpty;
 
 public record ConnectionRequest(
-                @NotBlank(message = "App URL is mandatory") String appUrl,
-                @NotBlank(message = "Username is mandatory") String username,
-                @NotBlank(message = "Password is mandatory") String password) {
+        @NotBlank(message = "App URL is mandatory") String appUrl,
+        @NotBlank String serviceType, 
+        @NotEmpty Map <String, String> credentials,
+        boolean stayLoggedIn) {
 }