support PMTiles protocol

[benstonezhang]

support maps vector tiles from PMTiles file: url starts with string "pmtiles://"

below is a sample style file:

{
  "version": 8,
  "sources": {
    "example_maps": {
      "type": "vector",
      "url": "pmtiles://https://example.com/maps/pmtiles/region.pmtiles"
    }
  },
  "sprite": "/maps/style/protomaps_v4_light",
  "glyphs": "/maps/fonts/{fontstack}/{range}.pbf",
  "layers": [
    {
      "id": "bg",
      "type": "background",
      "paint": {
        "background-color": "#F2EFE9"
      }
    },
    {
      "id": "ocean",
      "type": "fill",
      "source": "example_maps",
      "source-layer": "ocean",
      "paint": {
        "fill-color": "#AAD3DF"
      }
    },
    {
      "id": "water_polygons",
      "type": "fill",
      "source": "example_maps",
      "source-layer": "water_polygons",
      "paint": {
        "fill-color": "#AAD3DF"
      }
    },
    {
      "id": "boundaries",
      "type": "line",
      "source": "example_maps",
      "source-layer": "boundaries",
      "paint": {
        "line-color": "#8D618B"
      }
    },
    {
      "id": "streets",
      "type": "line",
      "source": "example_maps",
      "source-layer": "streets",
      "layout": {
        "visibility": "visible"
      },
      "paint": {
        "line-color": [
          "match",
          [
            "get",
            "kind"
          ],
          "motorway",
          "#e66e89",
          [
            "trunk",
            "primary",
            "secondary"
          ],
          "#f4c37d",
          "#ccccca"
        ]
      }
    },
    {
      "id": "places",
      "type": "symbol",
      "source": "example_maps",
      "source-layer": "place_labels",
      "layout": {
        "text-field": [
          "get",
          "name"
        ],
        "text-font": [
          "Open Sans Semibold"
        ],
        "text-size": 16
      },
      "paint": {
        "text-halo-width": 1,
        "text-halo-color": "rgba(255, 255, 255, 1)"
      }
    },
    {
      "id": "buildings",
      "type": "fill",
      "source": "example_maps",
      "source-layer": "buildings",
      "paint": {
        "fill-color": "#D9D0C9"
      }
    }
  ],
  "id": "example_maps-demo-maplibre"
}