Add a sindri clone CLI command

[sangaline]

This adds a sindri clone command which can be used to download either your own circuit or somebody else's public circuit. You can either specify an exact circuit UUID or DockerHub inspired identifiers like <circuit-name>, <circuit-name>:<tag>, <team>/<circuit-name>, or <team>/<circuit-name>:<tag>.

Usage: sindri clone [options] <circuit> [directory]

Clone a circuit into a local directory.

Arguments:
circuit     The circuit to clone.
directory   The directory to clone the circuit into.

Options:
-h, --help  display help for command

I haven't added it to the SDK yet, we'll need to think about a good interface to simultaneously support browser and node there. The auto-generated internal API client unfortunately required a number of modifications in order to support streaming responses which are necessary for very large circuit packages. These are starting to build up, and we need to think about ways to generalize these diff patches as part of the generation process. The openapi-typescript-codegen codebase is unfortunately really complicated, so it's not practical to fork or patch it directly.

[sangaline]

Semi-unrelated, but I think these are actually useful to have in the package now that we have the clone capability.

[jason-sindri]

lgtm