Create side panel & global popup

Create a side panel UI element for desktop with three buttons for:
adding a column, settings, and account management. The account
management button is temporary pending a better design. It is the only
one that is interactable at the moment. When the user clicks it, the
global popup window will be shown and the AccountManagementView will be
presented on the window. The user can click on the X on the top right of
the window to close it.

Signed-off-by: kernelkind <kernelkind@gmail.com>
Signed-off-by: William Casarin <jb55@jb55.com>

src/ui_preview/main.rs

@@ -3,8 +3,8 @@ use notedeck::app_creation::{
 };
 use notedeck::ui::account_login_view::AccountLoginView;
 use notedeck::ui::{
-    AccountManagementView, AccountSelectionWidget, Preview, PreviewApp, ProfilePic, ProfilePreview,
-    RelayView,
+    AccountManagementView, AccountSelectionWidget, DesktopGlobalPopup, DesktopSidePanel, Preview,
+    PreviewApp, ProfilePic, ProfilePreview, RelayView,
 };
 use std::env;
 
@@ -88,5 +88,7 @@ async fn main() {
         ProfilePic,
         AccountManagementView,
         AccountSelectionWidget,
+        DesktopSidePanel,
+        DesktopGlobalPopup,
     );
 }