Provide a way to opt-out of pulling the precompiled binary

[nickdichev-firework]

I provide the lc binary to my dev environment and prod builds outside of mix. Since the binary is ~30MB its nice to be able to prune it from my docker images. Instead of having to manually do it it would be great if I could opt out of the mix compile forcing me to pull it.

I know you guys have a way to do this with the :membrane_precompiled config, perhaps that could be used?