Add ocaml-install command to install opam packages

[dmmulroy]

We want to add a new CLI command called ocaml-install to install dependencies from opam. In addition, we want to add npm scripts to the templated package.json to enable users to run the command. We will use this issue to track the progress.

see for original context: #60 (comment)

• [ocaml-install]: Add initial ocaml-install library #66
• [ocaml-install]: Implement Commander ocaml-install command #67
• [ocaml-install]: Create Add_dependency "Process" module in dune.ml #69
• [ocaml-install]: Add ocaml-install component/view + wire up to engine #68
• [ocaml-install]: Update package.json.tmpl to include ocaml-install scripts #70