Refactor MainForm class and add dependencies

Convert MainForm from partial to regular class, otherwise the InitializeComponent method would be overwritten by the designer. With changes, this method might be ready for the designer, but it currently isn't.

Author: christiannagel

src/Codebreaker.WinForms/MainForm.cs

@@ -6,7 +6,7 @@ namespace Codebreaker.WinForms;
 /// <summary>
 /// Main form for the Codebreaker game.
 /// </summary>
-public partial class MainForm : Form
+public class MainForm : Form
 {
     private readonly GamePageViewModel _viewModel;
     private readonly IInfoBarService _infoBarService;