feat: add unknown .mrpack install warning modal (#5942)

* Update modpack button copy

* Change outlined button style for standard buttons

* add unknown pack warning modal

* implementation

* Redo download toasts

* prepr

* improve hit area of window controls

* implement "don't show again"

* prepr

* duplicate modal ref declarations

* increase spacing of progress items

* address truman review

apps/app-frontend/src/store/theme.ts

@@ -7,6 +7,8 @@ export const DEFAULT_FEATURE_FLAGS = {
 	worlds_in_home: true,
 	server_project_qa: false,
 	server_ram_as_bytes_always_on: false,
+	always_show_app_controls: false,
+	skip_unknown_pack_warning: false,
 	i18n_debug: false,
 }