Simplified Sliding Sync (#28515)

* Experimental SSS

Working branch to get SSS functional on element-web.

Requires https://github.com/matrix-org/matrix-js-sdk/pull/4400

* Adjust tests to use new behaviour

* Remove well-known proxy URL lookup; always use native

This is actually required for SSS because otherwise it would use
the proxy over native support.

* Linting

* Debug logging

* Control the race condition when swapping between rooms

* Dont' filter by space as synapse doesn't support it

* Remove SS code related to registering lists and managing ranges

- Update the spidering code to spider all the relevant lists.
- Add canonical alias to the required_state to allow room name calcs to work.

Room sort order is busted because we don't yet look at `bump_stamp`.

* User bumpStamp if it is present

* Drop initial room load from 20 per list to 10

* Half the batch size to trickle more quickly

* Prettier

* prettier on tests too

* Remove proxy URL & unused import

* Hopefully fix tests to assert what the behaviour is supposed to be

* Move the singleton to the manager tyo fix import loop

* Very well, code, I will remove you

Why were you there in the first place?

* Strip out more unused stuff

* Fix playwright test

Seems like this lack of order updating unless a room is selected
was just always a bug with both regular and non-sliding sync. I
have no idea how the test passed on develop because it won't run.

* Fix test to do maybe what it was supposed to do... possibly?

* Remove test for old pre-simplified sliding sync behaviour

* Unused import

* Remove sliding sync proxy & test

I was wrong about what this test was asserting, it was suposed
to assert that notification dots aren't shown (because SS didn't
support them somehow I guess) but they are fine in SSS so the test
is just no longer relevant.

* Remove now pointless credentials

* Remove subscription removal as SSS doesn't do that

* Update tests

* add test

* Switch to new labs flag & break if old labs flag is enabled

* Remove unused import & fix test

* Fix other test

* Remove name & description from old labs flag

as they're not displayed anywhere so not useful

* Remove old sliding sync option

by making it not a feature

* Add back unread nindicator test but inverted

and minus the bit about disabling notification which surely would have
defeated the original point anyway?

* Reinstate test for room_subscriptions

...and also make tests actually use sliding sync

* Use UserFriendlyError

* Remove empty constructor

* Remove unrelated changes

* Unused import

* Fix import

* Avoid moving import

---------

Co-authored-by: Kegan Dougal <7190048+kegsay@users.noreply.github.com>

test/unit-tests/hooks/useSlidingSyncRoomSearch-test.tsx

@@ -1,84 +0,0 @@
-/*
-Copyright 2024 New Vector Ltd.
-Copyright 2023 The Matrix.org Foundation C.I.C.
-
-SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
-Please see LICENSE files in the repository root for full details.
-*/
-
-import { waitFor, renderHook, act } from "jest-matrix-react";
-import { mocked } from "jest-mock";
-import { type SlidingSync } from "matrix-js-sdk/src/sliding-sync";
-import { Room } from "matrix-js-sdk/src/matrix";
-
-import { useSlidingSyncRoomSearch } from "../../../src/hooks/useSlidingSyncRoomSearch";
-import { MockEventEmitter, stubClient } from "../../test-utils";
-import { SlidingSyncManager } from "../../../src/SlidingSyncManager";
-
-describe("useSlidingSyncRoomSearch", () => {
-    afterAll(() => {
-        jest.restoreAllMocks();
-    });
-
-    it("should display rooms when searching", async () => {
-        const client = stubClient();
-        const roomA = new Room("!a:localhost", client, client.getUserId()!);
-        const roomB = new Room("!b:localhost", client, client.getUserId()!);
-        const slidingSync = mocked(
-            new MockEventEmitter({
-                getListData: jest.fn(),
-            }) as unknown as SlidingSync,
-        );
-        jest.spyOn(SlidingSyncManager.instance, "ensureListRegistered").mockResolvedValue({
-            ranges: [[0, 9]],
-        });
-        SlidingSyncManager.instance.slidingSync = slidingSync;
-        mocked(slidingSync.getListData).mockReturnValue({
-            joinedCount: 2,
-            roomIndexToRoomId: {
-                0: roomA.roomId,
-                1: roomB.roomId,
-            },
-        });
-        mocked(client.getRoom).mockImplementation((roomId) => {
-            switch (roomId) {
-                case roomA.roomId:
-                    return roomA;
-                case roomB.roomId:
-                    return roomB;
-                default:
-                    return null;
-            }
-        });
-
-        // first check that everything is empty
-        const { result } = renderHook(() => useSlidingSyncRoomSearch());
-        const query = {
-            limit: 10,
-            query: "foo",
-        };
-        expect(result.current.loading).toBe(false);
-        expect(result.current.rooms).toEqual([]);
-
-        // run the query
-        act(() => {
-            result.current.search(query);
-        });
-
-        // wait for loading to finish
-        await waitFor(() => {
-            expect(result.current.loading).toBe(false);
-        });
-
-        // now we expect there to be rooms
-        expect(result.current.rooms).toEqual([roomA, roomB]);
-
-        // run the query again
-        act(() => {
-            result.current.search(query);
-        });
-        await waitFor(() => {
-            expect(result.current.loading).toBe(false);
-        });
-    });
-});