Migrate component library entirely to `@material/web` once we drop support for iOS 15

[daniellacosse]

Currently we cannot fully embrace the @material/web components as they are only partially functional on iOS 15.x. Using webpack to force all our copies of lit into one version had some effect, but there are still cases in which these components don't fully work on this platform - see #2334 for context.

Describe the solution you'd like.

Once we are ready to drop support for iOS 15, we should then upgrade all our components to @material/web. This should allow us to naturally adopt one version of Lit, and we can remove the webpack override.