Replace OEmbed and initial state Rabl templates with serializers (#4110)

* Replace OEmbed Rabl template with serializer

* Replace initial state rabl with serializer

app/views/home/index.html.haml

@@ -1,5 +1,5 @@
 - content_for :header_tags do
-  %script#initial-state{ type: 'application/json' }!= json_escape(render(file: 'home/initial_state', formats: :json))
+  %script#initial-state{ type: 'application/json' }!= json_escape(@initial_state_json)
 
   = javascript_pack_tag 'application', integrity: true, crossorigin: 'anonymous'
 

app/views/home/initial_state.json.rabl

@@ -1,38 +0,0 @@
-object false
-
-node(:meta) do
-  {
-    streaming_api_base_url: @streaming_api_base_url,
-    access_token: @token,
-    locale: I18n.locale,
-    domain: site_hostname,
-    me: current_account.id,
-    admin: @admin.try(:id),
-    boost_modal: current_account.user.setting_boost_modal,
-    delete_modal: current_account.user.setting_delete_modal,
-    auto_play_gif: current_account.user.setting_auto_play_gif,
-    system_font_ui: current_account.user.setting_system_font_ui,
-  }
-end
-
-node(:compose) do
-  {
-    me: current_account.id,
-    default_privacy: current_account.user.setting_default_privacy,
-  }
-end
-
-node(:accounts) do
-  store = {}
-  store[current_account.id] = ActiveModelSerializers::SerializableResource.new(current_account, serializer: REST::AccountSerializer)
-  store[@admin.id] = ActiveModelSerializers::SerializableResource.new(@admin, serializer: REST::AccountSerializer) unless @admin.nil?
-  store
-end
-
-node(:media_attachments) do
-  {
-    accept_content_types: MediaAttachment::IMAGE_MIME_TYPES + MediaAttachment::VIDEO_MIME_TYPES
-  }
-end
-
-node(:settings) { @web_settings }