Update build process

I'm helping Google Fonts to sort out `stat` table issues across the variable fonts library, and found that Inconsolata has an odd situation going on where "Regular" and "Bold" appear twice in Mac Word (We are testing in Mac Word as it is the most particular environment to ensure `fvar` and `stat` are in alignment.):

I believe that this is due to the presence of the "Ligconsolata" instances that are in the Glyphs file. While these are fine for static generation, in a variable font situation they're adding unnecessary noise / confusion and it would be better to remove them—instead creating the Ligconsolata variants during the build process from the base version.

If you are open to this, I am happy to offer my help in updating the build process to enable it.

Additionally, I might suggest splitting the build process in two—a first step that converts the Glyphs file to UFOs (which must be done via Glyphs to process the corner components) and a second step that then builds from the UFOs. This would allow folks to build the font from any device rather than requiring a Mac to do so.