Add build Command

[jmwright]

This command would amalgamate models and data files into their compiled versions in the dist directory. The first one to be called will be the the sliderule-rs build_bom function from the issue here.

[jmwright]

The cargo CLI can use other CLIs as if they're commands if their names are prefixed with cargo- and they're in the PATH. It seems like that same method could work well for the Sliderule build system. The build command could be it's own CLI with it's own support crate(s), but act like it's part of sliderule-cli to give a more cohesive UX.

https://doc.rust-lang.org/book/ch14-05-extending-cargo.html

Workspaces might also be tangentially related to this to organize the crates in repos as well.

https://doc.rust-lang.org/book/ch14-03-cargo-workspaces.html