OEmbed support for PreviewCard (#2337)

* OEmbed support for PreviewCard

* Improve ProviderDiscovery code failure treatment

* Do not crawl links if there is a content warning, since those
don't display a link card anyway

* Reset db schema

* Fresh migrate

* Fix rubocop style issues
Fix #1681 - return existing access token when applicable instead of creating new

* Fix test

* Extract http client to helper

* Improve oembed controller

app/services/follow_remote_account_service.rb

@@ -2,6 +2,7 @@
 
 class FollowRemoteAccountService < BaseService
   include OStatus2::MagicKey
+  include HttpHelper
 
   DFRN_NS = 'http://purl.org/macgirvin/dfrn/1.0'
 
@@ -73,7 +74,7 @@ class FollowRemoteAccountService < BaseService
   end
 
   def get_feed(url)
-    response = http_client.get(Addressable::URI.parse(url).normalize)
+    response = http_client(write: 20, connect: 20, read: 50).get(Addressable::URI.parse(url).normalize)
     [response.to_s, Nokogiri::XML(response)]
   end
 
@@ -98,8 +99,4 @@ class FollowRemoteAccountService < BaseService
   def get_profile(body, account)
     RemoteProfileUpdateWorker.perform_async(account.id, body.force_encoding('UTF-8'), false)
   end
-
-  def http_client
-    HTTP.timeout(:per_operation, write: 20, connect: 20, read: 50)
-  end
 end