Added LinkTimeline and PreviewCard fetching by id

• Added:
- LinkTimeline and PreviewCard fetching by id

app/controllers/api/v1/links_controller.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class Api::V1::LinksController < Api::BaseController
+  before_action :require_user!
+  before_action :set_link
+
+  def show
+    render json: @link, serializer: REST::PreviewCardSerializer
+  end
+
+  private
+
+  def set_link
+    @link = PreviewCard.find(params[:id])
+  end
+
+end