Bug 1869833 - Remove all legacy Firefox View files and assets. r=sfoster,fxview-reviewers,extension-reviewers

- removes all old View related files and assets
- removes legacy telemetry
- removes tests related to prefs that have since been removed
- remove `browser_all_files_referenced.js` exceptions added in Bug 1869833

Depends on D196093

Differential Revision: https://phabricator.services.mozilla.com/D196208

browser/components/firefoxview/firefoxview.mjs

@@ -1,36 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-window.addEventListener("DOMContentLoaded", async () => {
-  Services.telemetry.recordEvent("firefoxview", "entered", "firefoxview", null);
-  if (Cu.isInAutomation) {
-    Services.obs.notifyObservers(null, "firefoxview-entered");
-    document.addEventListener("visibilitychange", () => {
-      if (document.visibilityState === "visible") {
-        Services.obs.notifyObservers(null, "firefoxview-entered");
-      }
-    });
-  }
-
-  document.getElementById("recently-closed-tabs-container").onLoad();
-  // If Firefox View was reloaded by the user, force syncing of tabs
-  // to get the most up to date synced tabs.
-  if (
-    performance
-      .getEntriesByType("navigation")
-      .map(nav => nav.type)
-      .includes("reload")
-  ) {
-    await document.getElementById("tab-pickup-container").onReload();
-  }
-});
-
-window.addEventListener("unload", () => {
-  const tabPickupList = document.querySelector("tab-pickup-list");
-  if (tabPickupList) {
-    tabPickupList.cleanup();
-  }
-  document.getElementById("tab-pickup-container").cleanup();
-  document.getElementById("recently-closed-tabs-container").cleanup();
-});