[Feature Request] Tracking with Matomo

**Is your feature request related to a problem? Please describe.**
Recently, the ability to add Google Analystics tracking was added in #8733. It would be nice to have the possibility to also use alternative trackers such as [Matomo](https://matomo.org/).

**Describe the solution you'd like**
Ideally, we could set the tracker url and site id in the docfx config and docfx would include the corresponding javascript tracking code in the output.

**Describe alternatives you've considered**
The alternative is to add the tracking code to a custom template

**Additional context**