feat: add WebFrameMain detached property (#43473)

* feat: add WebFrameMain detached property

fix: throw instead of returning null senderFrame

test: detached frames

fix: ensure IPCs of pending deletion RFHs are dispatched

fix: lookup WFM by FTN ID to dispatch IPCs

feat: add frame.isDestroyed()

return null

fix: return undefined

docs: add null to all frame properties

refactor: option c, return null and emit warning

refactor: add routingId & processId to navigation events

test: null frame property

docs: clarify warning message

better wording

clarify null frame

fix: browserwindow spec

* maybe fix 🤷

* fix: use updated util #43722

* docs: add notice for frame change of behavior

* docs: clarify why frame properties may be null

* lint

* wip

* fix: content::FrameTreeNodeId lookup and converter

* refactor: avoid holey array deoptimization

---------

Co-authored-by: John Kleinschmidt <jkleinsc@electronjs.org>

spec/api-browser-window-spec.ts

@@ -591,7 +591,7 @@ describe('BrowserWindow module', () => {
         it('is triggered when a cross-origin iframe navigates _top', async () => {
           w.loadURL(`data:text/html,<iframe src="http://127.0.0.1:${(server.address() as AddressInfo).port}/navigate-top"></iframe>`);
           await emittedUntil(w.webContents, 'did-frame-finish-load', (e: any, isMainFrame: boolean) => !isMainFrame);
-          let initiator: WebFrameMain | undefined;
+          let initiator: WebFrameMain | null | undefined;
           w.webContents.on('will-navigate', (e) => {
             initiator = e.initiator;
           });