[Epic] Create a new CLI for Unit (unitctl)

[callahad]

Consider the following projects: Rustup, K3d, Kind, Linkerd, and Caddy.

Each of these projects needs only one single command to start using the product. None of these products require involved modifications to the host system and they all work on multiple commonly used platforms. Our services NGINX Service Mesh (rest in peace) and NGINX Kubernetes Ingress Controller also had easy startup processes.

Having a simple and efficient discovery to deployment process would enable our product to end up in more proofs of concept, more MVPs, and thus attached to more applications. Busy developers who would prefer to focus on implementing their own designs will prefer alternative app servers.

TODO: Refine / cluster these into stories

• CLI: Upgrade Hyper version. #1245
• CLI: Refactor custom error structures #1246
• CLI Feature: make read only application mount configurable #1247
• CLI: customize openapi generator #1248
• CLI: make application directory optional #1249
• CLI: dont require mac users to install additional versions of coreutilities #1251
• CLI: instances listening on TCP ports are shown as unix sockets #1266
• CLI: New subcommand for restarting applications #1279
• CLI: New subcommand for listing applications #1280
• CLI: Update all docs to use unitctl
• CLI: Build and release RISC-V binaries
• CLI: Include unitctl in our Homebrew and Linux packages #1281
• CLI: Deprecate unitc
• CLI: subcommand for saving configuration #1317
• CLI: deploy configuration to many instances #1318
• CLI: SSH Support #1319