ts: Migrate setup.js to typescript.

Also added global type definition for `get_offset_to_window`
helper function.

tools/test-js-with-node

@@ -181,7 +181,7 @@ EXEMPT_FILES = make_set(
         "web/src/settings_user_groups_legacy.js",
         "web/src/settings_user_topics.js",
         "web/src/settings_users.js",
-        "web/src/setup.js",
+        "web/src/setup.ts",
         "web/src/spectators.js",
         "web/src/spoilers.ts",
         "web/src/starred_messages_ui.js",

web/src/global.d.ts

@@ -15,6 +15,7 @@ type JQueryCaretRange = {
 // eslint-disable-next-line @typescript-eslint/consistent-type-definitions
 interface JQuery {
     expectOne(): JQuery;
+    get_offset_to_window(): DOMRect;
     tab(action?: string): this; // From web/third/bootstrap
     modal(action?: string): this; // From web/third/bootstrap
 

web/src/page_params.ts

@@ -16,6 +16,8 @@ export const page_params: {
     is_moderator: boolean;
     is_owner: boolean;
     is_spectator: boolean;
+    needs_tutorial: boolean;
+    page_load_time: number;
     promote_sponsoring_zulip: boolean;
     realm_add_custom_emoji_policy: number;
     realm_avatar_changes_disabled: boolean;