Improve performance of RoomContext in RoomHeader (#28574)

* Improve performance of RoomContext in RoomHeader

This allows a component to subscribe to only part of the RoomContext so they do not need to re-render on every single change

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Update tests

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Prettier

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Iterate

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Add comment

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

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Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

test/unit-tests/components/views/rooms/MessageComposerButtons-test.tsx

@@ -10,11 +10,11 @@ import React from "react";
 import { render, screen, waitFor } from "jest-matrix-react";
 
 import MatrixClientContext from "../../../../../src/contexts/MatrixClientContext";
-import RoomContext from "../../../../../src/contexts/RoomContext";
 import { createTestClient, getRoomContext, mkStubRoom } from "../../../../test-utils";
 import { IRoomState } from "../../../../../src/components/structures/RoomView";
 import { MatrixClientPeg } from "../../../../../src/MatrixClientPeg";
 import MessageComposerButtons from "../../../../../src/components/views/rooms/MessageComposerButtons";
+import { ScopedRoomContextProvider } from "../../../../../src/contexts/ScopedRoomContext.tsx";
 
 describe("MessageComposerButtons", () => {
     // @ts-ignore - we're deliberately not implementing the whole interface here, but
@@ -54,7 +54,7 @@ describe("MessageComposerButtons", () => {
 
         return render(
             <MatrixClientContext.Provider value={mockClient}>
-                <RoomContext.Provider value={defaultRoomContext}>{component}</RoomContext.Provider>
+                <ScopedRoomContextProvider {...defaultRoomContext}>{component}</ScopedRoomContextProvider>
             </MatrixClientContext.Provider>,
         );
     }