Add preview of followers removed in domain block modal in web UI (#32032)

app/controllers/api/v1/domain_blocks/previews_controller.rb

app/javascript/mastodon/api.ts

app/javascript/mastodon/components/button.tsx

...avascript/mastodon/features/ui/components/block_modal.jsx

...pt/mastodon/features/ui/components/domain_block_modal.tsx

app/javascript/mastodon/locales/en.json

app/javascript/styles/mastodon/components.scss

app/javascript/styles/mastodon/variables.scss

app/presenters/domain_block_preview_presenter.rb

app/serializers/rest/domain_block_preview_serializer.rb

config/routes/api.rb