* add annotate to Gemfile
* rails g annotate:install
* configure annotate_models
* add schema info to models
* fix rubocop to add frozen_string_literal
* 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
Yamagishi Kazutoshi