PMTiles support

[martinRenou]

https://maplibre.org/maplibre-gl-js/docs/examples/pmtiles

See also how leafmap implements it using maplibre Python (very similar):

• examples https://leafmap.org/notebooks/82_pmtiles/
• implementation https://github.com/opengeos/leafmap/blob/e3e30d6f4ddd27d9ada0df737c8be3b14ce08504/leafmap/maplibregl.py#L1672

[martinRenou]

Note that this seems to not be supported by QGIS so our (future) qgis editor should probably not allow creating such layer

[gjmooney]

Added in #91