Refactor view source event to MVVM (#33428)

* Refactor view source event to MVVM

* remove unused variable since movement

* Update view source event screenshots

* Update packages/shared-components/src/room/timeline/event-tile/body/ViewSourceEventView/ViewSourceEventView.tsx

Co-authored-by: Florian Duros <florian.duros@ormaz.fr>

* Use view model disposables for source event decryption

* Consolidate source event view model updates

* Fix prettier

* Fix view source expanded class name

* Remove void from source event decryption

---------

Co-authored-by: Florian Duros <florian.duros@ormaz.fr>

apps/web/playwright/e2e/timeline/timeline.spec.ts

@@ -718,7 +718,7 @@ test.describe("Timeline", () => {
             await viewSourceEventExpanded.hover();
             const toggleEventButton = viewSourceEventExpanded.getByRole("button", { name: "toggle event" });
             // Check size and position of toggle on expanded view source event
-            // See: _ViewSourceEvent.pcss
+            // See: ViewSourceEventView.module.css
             await expect(toggleEventButton).toHaveCSS("height", "16px"); // --ViewSourceEvent_toggle-size
             await expect(toggleEventButton).toHaveCSS("align-self", "flex-end");
             // Click again to collapse the source