Add cookie popup to material.angular.io

[cindygk]

1. Create a cookie pop up for the site (in the style of https://web.dev)
2. Add the following text
   "This site uses cookies from Google to deliver its services and to analyze traffic.
   Learn more. Ok, Got it."
   Notes:
   Clicking the “Ok, Got it” button should dismiss the cookie bar. Clicking the “Ok, Got it” button should be recorded on the client (either local storage or cookie) so that we can remember the user’s choice and the user does not see the cookie bar again unless they have cleared their cookies.
   Note: there is no option to decline - only to "Learn More" or click "Ok, Got it."