add dto, refactor names, update controllers

src/main/java/com/faf223/expensetrackerfaf/dto/UserDTO.java

@@ -0,0 +1,13 @@
+package com.faf223.expensetrackerfaf.dto;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class UserDTO {
+    private String uuid;
+    private String name;
+    private String surname;
+    private String username;
+}