Make an embeddable template for Matomo

[elliot-sawyer]

The module currently loads the code securely via an extension rather than relying on template includes. This was done for CSP reasons, and is not for everybody. Refactor the code to allow an Include template to be manually embedded in the page:

• include <script> tag
• check for SiteConfig first
• document setup in readme
• should respect namespaces

Ideally it should behave the same way as GoogleAnalytics template in the CWP Starter Theme

Moreover, the existing template should be refactored to use an alternative name, but still be automatically embedded into the page