Store refactor: use non-global stores in components (#9293)

* Add Stores and StoresContext and use it in MatrixChat and RoomView

Added a new kind of class:
- Add God object `Stores` which will hold refs to all known stores and the `MatrixClient`. This object is NOT a singleton.
- Add `StoresContext` to hold onto a ref of `Stores` for use inside components.

`StoresContext` is created via:
- Create `Stores` in `MatrixChat`, assigning the `MatrixClient` when we have one set. Currently sets the RVS to `RoomViewStore.instance`.
- Wrap `MatrixChat`s `render()` function in a `StoresContext.Provider` so it can be used anywhere.

`StoresContext` is currently only used in `RoomView` via the following changes:
- Remove the HOC, which redundantly set `mxClient` as a prop. We don't need this as `RoomView` was using the client from `this.context`.
- Change the type of context accepted from `MatrixClientContext` to `StoresContext`.
- Modify alllll the places where `this.context` is used to interact with the client and suffix `.client`.
- Modify places where we use `RoomViewStore.instance` and replace them with `this.context.roomViewStore`.

This makes `RoomView` use a non-global instance of RVS.

* Linting

* SDKContext and make client an optional constructor arg

* Move SDKContext to /src/contexts

* Inject all RVS deps

* Linting

* Remove reset calls; deep copy the INITIAL_STATE to avoid test pollution

* DI singletons used in RoomView; DI them in RoomView-test too

* Initial RoomViewStore.instance after all files are imported to avoid cyclical deps

* Lazily init stores to allow for circular dependencies

Rather than stores accepting a list of other stores in their constructors,
which doesn't work when A needs B and B needs A, make new-style stores simply
accept Stores. When a store needs another store, they access it via `Stores`
which then lazily constructs that store if it needs it. This breaks the
circular dependency at constructor time, without needing to introduce
wiring diagrams or any complex DI framework.

* Delete RoomViewStore.instance

Replaced with Stores.instance.roomViewStore

* Linting

* Move OverridableStores to test/TestStores

* Rejig how eager stores get made; don't automatically do it else tests break

* Linting

* Linting and review comments

* Fix new code to use Stores.instance

* s/Stores/SdkContextClass/g

* Update docs

* Remove unused imports

* Update src/stores/RoomViewStore.tsx

Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>

* Remove empty c'tor to make sonar happy

Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>

src/SlashCommands.tsx

@@ -62,7 +62,6 @@ import InfoDialog from "./components/views/dialogs/InfoDialog";
 import SlashCommandHelpDialog from "./components/views/dialogs/SlashCommandHelpDialog";
 import { shouldShowComponent } from "./customisations/helpers/UIComponents";
 import { TimelineRenderingType } from './contexts/RoomContext';
-import { RoomViewStore } from "./stores/RoomViewStore";
 import { XOR } from "./@types/common";
 import { PosthogAnalytics } from "./PosthogAnalytics";
 import { ViewRoomPayload } from "./dispatcher/payloads/ViewRoomPayload";
@@ -70,6 +69,7 @@ import VoipUserMapper from './VoipUserMapper';
 import { htmlSerializeFromMdIfNeeded } from './editor/serialize';
 import { leaveRoomBehaviour } from "./utils/leave-behaviour";
 import { isLocalRoom } from './utils/localRoom/isLocalRoom';
+import { SdkContextClass } from './contexts/SDKContext';
 
 // XXX: workaround for https://github.com/microsoft/TypeScript/issues/31816
 interface HTMLInputEvent extends Event {
@@ -209,7 +209,7 @@ function successSync(value: any) {
 
 const isCurrentLocalRoom = (): boolean => {
     const cli = MatrixClientPeg.get();
-    const room = cli.getRoom(RoomViewStore.instance.getRoomId());
+    const room = cli.getRoom(SdkContextClass.instance.roomViewStore.getRoomId());
     return isLocalRoom(room);
 };
 
@@ -868,7 +868,7 @@ export const Commands = [
         description: _td('Define the power level of a user'),
         isEnabled(): boolean {
             const cli = MatrixClientPeg.get();
-            const room = cli.getRoom(RoomViewStore.instance.getRoomId());
+            const room = cli.getRoom(SdkContextClass.instance.roomViewStore.getRoomId());
             return room?.currentState.maySendStateEvent(EventType.RoomPowerLevels, cli.getUserId())
                 && !isLocalRoom(room);
         },
@@ -909,7 +909,7 @@ export const Commands = [
         description: _td('Deops user with given id'),
         isEnabled(): boolean {
             const cli = MatrixClientPeg.get();
-            const room = cli.getRoom(RoomViewStore.instance.getRoomId());
+            const room = cli.getRoom(SdkContextClass.instance.roomViewStore.getRoomId());
             return room?.currentState.maySendStateEvent(EventType.RoomPowerLevels, cli.getUserId())
                 && !isLocalRoom(room);
         },