[PM-22180] Setup Extension Videos (#15419)

* remove placeholder image

* add videos for setup extension

* add support for mobile viewports

* add mobile/responsiveness for setup extension page

* add videos from `assets.bitwarden.com`

* align with figma for borders and shadow

* make text responsive for setup headings

* remove period

* add tests

* add tests for video sequence

* force font weight on `h2`

* add 8px to bottom margin of video container

apps/web/src/app/vault/components/setup-extension/setup-extension.component.spec.ts

@@ -27,6 +27,7 @@ describe("SetupExtensionComponent", () => {
     navigate.mockClear();
     openExtension.mockClear();
     getFeatureFlag.mockClear().mockResolvedValue(true);
+    window.matchMedia = jest.fn().mockReturnValue(false);
 
     await TestBed.configureTestingModule({
       imports: [SetupExtensionComponent, RouterModule.forRoot([])],