Re-instate some kind of project init commands

[alerque]

There used to be a casile make init rule to do things like install fonts or node deps or whatever. With CaSILE itself now being self contained that init is baked into the build system. But that only works for CaSILE itself. Along the way we actually lost the ability to hook onto that init step to install project or publisher specific dependencies.

I think the new casile setup command should have a hook of some kind to run project or publisher specific toolkit init commands. A notable thing this could do in use yarn/nmp to fetch font dependencies from @fontsource.