Modify config for proper Gradle usage

Gradle run and shadowJar tasks are not functioning as intended.

This should be fixed for ease of use and to create a new JAR release.

Let's edit the build.gradle for proper main class declaration.
Also,let's fix any checkstyle errors that might inhibit the build process.

build.gradle

@@ -44,7 +44,7 @@ test {
 }
 
 application {
-    mainClassName = "seedu.duke.Duke"
+    mainClassName = "duke.Launcher"
 }
 
 shadowJar {

src/main/java/duke/Command/AddCommand.java

@@ -1,6 +1,10 @@
 package duke.Command;
 
-import duke.*;
+import duke.DukeException;
+import duke.Storage;
+import duke.Task;
+import duke.TaskList;
+import duke.Ui;
 
 public class AddCommand extends Command {
     private String type;

src/main/java/duke/Command/DeleteCommand.java

@@ -1,6 +1,10 @@
 package duke.Command;
 
-import duke.*;
+import duke.DukeException;
+import duke.Storage;
+import duke.Task;
+import duke.TaskList;
+import duke.Ui;
 
 public class DeleteCommand extends Command {
     private int index;

src/main/java/duke/Command/DoneCommand.java

@@ -1,6 +1,10 @@
 package duke.Command;
 
-import duke.*;
+import duke.DukeException;
+import duke.Storage;
+import duke.Task;
+import duke.TaskList;
+import duke.Ui;
 
 public class DoneCommand extends Command {
 

src/main/java/duke/Command/FindCommand.java

@@ -2,7 +2,11 @@
 
 import java.util.ArrayList;
 
-import duke.*;
+import duke.DukeException;
+import duke.Storage;
+import duke.Task;
+import duke.TaskList;
+import duke.Ui;
 
 
 public class FindCommand extends Command {

src/main/java/duke/MainWindow.java

@@ -1,7 +1,5 @@
 package duke;
 
-import duke.DialogBox;
-import duke.Duke;
 import javafx.fxml.FXML;
 import javafx.scene.control.Button;
 import javafx.scene.control.ScrollPane;
@@ -50,4 +48,4 @@ private void handleUserInput() {
         );
         userInput.clear();
     }
-}
+}

src/main/java/duke/Parser.java

@@ -1,6 +1,12 @@
 package duke;
 
-import duke.Command.*;
+import duke.Command.AddCommand;
+import duke.Command.Command;
+import duke.Command.DeleteCommand;
+import duke.Command.DoneCommand;
+import duke.Command.ExitCommand;
+import duke.Command.FindCommand;
+import duke.Command.ListCommand;
 
 
 public class Parser {

src/test/java/dukeTest/TaskListTest.java

@@ -1,13 +1,16 @@
 package dukeTest;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.ArrayList;
+
+import org.junit.jupiter.api.Test;
+
 import duke.DukeException;
 import duke.Task;
 import duke.TaskList;
-import org.junit.jupiter.api.Test;
 
-import java.util.ArrayList;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class TaskListTest {
     @Test
@@ -20,7 +23,7 @@ public void addTaskTest() throws DukeException {
     }
 
     @Test
-    public void removeTaskTest() throws DukeException{
+    public void removeTaskTest() throws DukeException {
         Task task = new Task.Deadline("test", false, "2021-12-12");
         ArrayList<Task> temp = new ArrayList<>();
         temp.add(task);

src/test/java/dukeTest/TaskTest.java

@@ -1,9 +1,13 @@
 package dukeTest;
 
-import duke.Task;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
+import duke.Task;
+
+
+
 
 public class TaskTest {
     @Test