Add support for vector tiles

[giswqs]

This PR adds support for rendering vector tiles.

For ipyleaflet

import leafmap
m = leafmap.Map()
url = "https://tile.nextzen.org/tilezen/vector/v1/512/all/{z}/{x}/{y}.mvt?api_key=gCZXZglvRQa6sB2z7JzL1w"
m.add_vector_tile(url, layer_name='Vector Tile')
m

For folium

import leafmap.foliumap as leafmap
m = leafmap.Map()
url = "https://tile.nextzen.org/tilezen/vector/v1/512/all/{z}/{x}/{y}.mvt?api_key=gCZXZglvRQa6sB2z7JzL1w"
m.add_vector_tile(url, layer_name='Vector Tile')
m

Note that the ipyleaflet vector tile layer does support opacity or visible attributes.
Also, the folium VectorGridProtobuf does not work properly with LayerControl
python-visualization/folium#1716