Add CLI that optimizes an mbtiles of vector tiles

[springmeyer]

A CLI tool that runs this module over an entire tileset in an mbtiles file would be a useful way of exploring optimizations and optimizing entire outputs from tile generators like tippecanoe.

The CLI could be:

./bin/optimize-mbtiles.js [style.json] [input.mbtiles] [output.mbtiles] 

By default it would require writing a new mbtiles. But potentially it could accept an option to overwrite the existing mbtiles with optimized tiles (for the very experienced user).

[indus]

https://github.com/ibesora/vt-optimizer