Rework Upload internals to use MVVM (#33307)

* Initial reword of upload to MVVM.

* Update tests

* More incremental improvements

* Refactor tests to use helper method for composer uploads.

* Add drag and drop tests

* lint

* Add commentary

* fixup test

* More precise selector

* Retarget uploads

* lint

* fixup

* one more type

* update snap

* Fixup composerUploadFiles

* fix import

* lint

* Copy and paste fixes too

* Add tests for pasting

* Add tests for pasting files.

* Remove redundant fn

* rm comment

* tidy up

* Test cleanup

* More clean up

* another fix

* Use condensed version

* Cleanup tests

* more cleaning

* last bity

* s/throw Error/throw new Error/

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

@@ -14,7 +14,8 @@ import { createTestClient, getRoomContext, mkStubRoom } from "../../../../test-u
 import { MatrixClientPeg } from "../../../../../src/MatrixClientPeg";
 import MessageComposerButtons from "../../../../../src/components/views/rooms/MessageComposerButtons";
 import { ScopedRoomContextProvider } from "../../../../../src/contexts/ScopedRoomContext.tsx";
-import type { RoomContextType } from "../../../../../src/contexts/RoomContext.ts";
+import { type RoomContextType } from "../../../../../src/contexts/RoomContext.ts";
+import { RoomUploadContextProvider } from "../../../../../src/viewmodels/room/RoomUploadViewModel.tsx";
 
 describe("MessageComposerButtons", () => {
     // @ts-ignore - we're deliberately not implementing the whole interface here, but
@@ -54,7 +55,9 @@ describe("MessageComposerButtons", () => {
 
         return render(
             <MatrixClientContext.Provider value={mockClient}>
-                <ScopedRoomContextProvider {...defaultRoomContext}>{component}</ScopedRoomContextProvider>
+                <ScopedRoomContextProvider {...defaultRoomContext}>
+                    <RoomUploadContextProvider>{component}</RoomUploadContextProvider>
+                </ScopedRoomContextProvider>
             </MatrixClientContext.Provider>,
         );
     }