Change public accounts pages to mount the web UI (#19319)

* Change public accounts pages to mount the web UI

* Fix handling of remote usernames in routes

- When logged in, serve web app
- When logged out, redirect to permalink
- Fix `app-body` class not being set sometimes due to name conflict

* Fix missing `multiColumn` prop

* Fix failing test

* Use `discoverable` attribute to control indexing directives

* Fix `<ColumnLoading />` not using `multiColumn`

* Add `noindex` to accounts in REST API

* Change noindex directive to not be rendered by default before a route is mounted

* Add loading indicator for detailed status in web UI

* Fix missing indicator appearing while account is loading in web UI

spec/controllers/following_accounts_controller_spec.rb

@@ -34,27 +34,6 @@ describe FollowingAccountsController do
           expect(response).to have_http_status(403)
         end
       end
-
-      it 'assigns follows' do
-        expect(response).to have_http_status(200)
-
-        assigned = assigns(:follows).to_a
-        expect(assigned.size).to eq 2
-        expect(assigned[0]).to eq follow1
-        expect(assigned[1]).to eq follow0
-      end
-
-      it 'does not assign blocked users' do
-        user = Fabricate(:user)
-        user.account.block!(followee0)
-        sign_in(user)
-
-        expect(response).to have_http_status(200)
-
-        assigned = assigns(:follows).to_a
-        expect(assigned.size).to eq 1
-        expect(assigned[0]).to eq follow1
-      end
     end
 
     context 'when format is json' do