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/test-utils/test-utils.ts

@@ -659,8 +659,8 @@ export function mkMessage({
 
 export function mkStubRoom(
     roomId: string | null | undefined = null,
-    name: string | undefined,
-    client: MatrixClient | undefined,
+    name?: string | undefined,
+    client?: MatrixClient | undefined,
     state?: RoomState | undefined,
 ): Room {
     const stubTimeline = {