clapper-app: Add auto window resize keyboard shortcut

In addition to middle click, also add "Super+r" keyboard shortcut to perform window resize to fit video action

src/bin/clapper-app/clapper-app-application.c

@@ -700,6 +700,7 @@ clapper_app_application_constructed (GObject *object)
     { "app.preferences", { "<Control>comma", NULL, NULL }},
     { "app.about", { "F1", NULL, NULL }},
     { "win.toggle-fullscreen", { "F11", "f", NULL }},
+    { "win.auto-resize", { "<Super>r", NULL, NULL }},
     { "win.show-help-overlay", { "<Control>question", NULL, NULL }},
     { "window.close", { "<Control>q", "q", NULL }},
   };