Original commit: qgis/QGIS@81aa143 by rldhont

In QGIS Server 3.4, the WMTS API has been added in which the tile matrices are calculated except fro EPSG:3857 and EPSG:4326.

This commit adds the capability to select the tile matrices to use with the project and to configure the top-left corner and the last level of the tile matrix. In the case of EPSG:3857 and EPSG:4326, the user can only choose the last level of the tile matrices.

Funded by Ifremer.