Add voltages filtering argument - #4

I propose to add a voltage filtering for both single queries on Overpass and tile queries for osmnx.

It adds an argument --only-voltages which receive a coma-separated list of voltages. It matches all involved features so it can be combined with --include-cables.

The issue was some cables are part of distribution grids and produced unneeded glitches when included.
For instance, with --include-cables only:
image

And now much better with --include-cables --only-voltages 400000,225000,150000,90000,63000,45000,42000:
image

It paves the way for more macro args like --transmission or --distribution if necessary.