Redesign forms, verify link ownership with rel="me" (#8703)

* Verify link ownership with rel="me"

* Add explanation about verification to UI

* Perform link verifications

* Add click-to-copy widget for verification HTML

* Redesign edit profile page

* Redesign forms

* Improve responsive design of settings pages

* Restore landing page sign-up form

* Fix typo

* Support <link> tags, add spec

* Fix links not being verified on first discovery and passive updates

app/services/activitypub/process_account_service.rb

@@ -34,6 +34,7 @@ class ActivityPub::ProcessAccountService < BaseService
     after_protocol_change! if protocol_changed?
     after_key_change! if key_changed? && !@options[:signed_with_known_key]
     check_featured_collection! if @account.featured_collection_url.present?
+    check_links! unless @account.fields.empty?
 
     @account
   rescue Oj::ParseError
@@ -99,6 +100,10 @@ class ActivityPub::ProcessAccountService < BaseService
     ActivityPub::SynchronizeFeaturedCollectionWorker.perform_async(@account.id)
   end
 
+  def check_links!
+    VerifyAccountLinksWorker.perform_async(@account.id)
+  end
+
   def actor_type
     if @json['type'].is_a?(Array)
       @json['type'].find { |type| ActivityPub::FetchRemoteAccountService::SUPPORTED_TYPES.include?(type) }