Implement a self-updating mechanism for Darklang's executable

[OceanOak]

Changelog:

CLI
- Implement a self-updating mechanism for Darklang's executable

Notes / things that needs to be fixed:

• The CLI should work even if the user has no internet connection available (maybe the self update will just fail and we continue running the commands?)

• On Windows, commands like uname -s, which determine the operating system, may not work. We might consider something like the following?

  let os = Stdlib.Process.runCommand "uname -s"
  if os.exitCode != 0L then 
  // try the windows equivalent command

  • code signing for mac