Added controller for FileUpload, refactor of main package, try to add forum system.

src/main/java/site/easystartup/web/project/dto/ParticipantDto.java

@@ -0,0 +1,17 @@
+package site.easystartup.web.project.dto;
+
+import lombok.Data;
+
+import javax.validation.constraints.NotNull;
+import java.io.Serializable;
+import java.util.Set;
+
+@Data
+public class ParticipantDto implements Serializable {
+    private final Long participantId;
+    @NotNull
+    private final String technology;
+    private final String nameOfPosition;
+    private final UserDto user;
+    private final Set<UserDto> requests;
+}