🎂 ForwardProxyView + HotkeysView + OnlineConfigView + VersionUpdatePromptView

- Infrastructure: use one HttpClient instance throughout the lifecycle
- Version update: rewrite the update service and add update prompt window
- Server sharing: add copy link button
- Dependencies: add ReactiveUI.Events.WPF, ReactiveUI.Fody, ReactiveUI.Validation, WPFLocalizeExtension, MdXaml