Creates a WMTS definition based on a URL (requests GetCapabilities).
The parameter typenames can be used to filter the available layers.
The parameter tilematrixset can be used to select a specific tilematrixset, otherwise
PlexMap will try to select the best one based on the CRS.
To connect to a password-protected WMTS, include the credentials directly in the URL:
https://username:password@example.com/wmts