The `init` command is subsumed as a new `deploy` command because there's no real reason to have
these separately; however, all the functionality from the `init` function in the `TestnetDeploy`
struct is still retained.

At this point, only the Terraform run is being performed. The Ansible run is still to follow.

This command will run a `terraform destroy`, delete the Terraform workspace, and clear out the
generated Ansible inventory files.

It will later be extended for AWS to clear out the created keypair.

This commit also changes the library code in the crate to make use of the `Error` type defined in
the crate rather than using `eyre` for generic errors. In doing so, we introduced a few specific
errors for failures in the deployment process.

The licensing verification tool was switched on the in the merge workflow to assist in providing the
relevant details.

* Provided LICENSE file with BSD-3-Clause license
* Provided copyright notices on source files
* Updated the README to include reference to the license
* Updated the Cargo.toml to include reference to the license