refactor!: replace Python CLI with one written in Go

[zshipko]

Removes the Python implementation of the CLI and replaces it with a Go version

• Makes it easier to install and distribute extism executable
• Uses Extism go-sdk to call functions
• Moves install/uninstall commands to be subcommands of lib
  • Also adds lib versions to list available versions and lib check to get the version of the current libextism installation
  • install provides more options to customize installation location
  • install with no version installs the latest release
  • install --version git or install --version latest install the latest build from github
• Works on Windows

[zshipko]

Merging this now, then I'll update the docs!