Embed modal (#4748)

* Embed modal

* Proxy OEmbed requests from web UI

app/controllers/api/web/embeds_controller.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class Api::Web::EmbedsController < Api::BaseController
+  respond_to :json
+
+  before_action :require_user!
+
+  def create
+    status = StatusFinder.new(params[:url]).status
+    render json: status, serializer: OEmbedSerializer, width: 400
+  rescue ActiveRecord::RecordNotFound
+    oembed = OEmbed::Providers.get(params[:url])
+    render json: Oj.dump(oembed.fields)
+  rescue OEmbed::NotFound
+    render json: {}, status: :not_found
+  end
+end