Add DAP code to site

[michelle-rago]

We'll follow Digital.gov's agency/sub-agency model.

<script
--
  | async
  | type="text/javascript"
  | id="_fed_an_ua_tag"
  | src="https://dap.digitalgov.gov/Universal-Federated-Analytics-Min.js?agency=GSA&subagency=TTS"
  | ></script>

[rphillippi]

I've confirmed with Emily and Jacob that the site will only have DAP.

[caleywoods]

This commit by @michelle-rago takes care of this. It makes use of the 11ty templates built-in support for enabling DAP.