Distribute language server via npm package

[rvanasa]

This PR exposes the new TypeScript-based language server as an npm package (tentatively named mo-ide) which can be used in place of the original binary which powers the dfx _language-service subcommand.

TODO:

• [x] Bundle the language server as a separate CLI
• [x] Support different transport options (currently stdio, node-ipc, and socket from vscode-languageserver)
• [x] Build standalone mo-ide binaries for GitHub releases (using pkg)
• [ ] Test the language server on Vim / Emacs
• [ ] Include patches for Vim / Emacs if necessary
• [ ] Add step-by-step instructions for configuring Vim / Emacs

Please leave a comment if you are interested in using the Motoko language server with Vim or Emacs. Thanks!

[rvanasa]

@ggreif, would you be interested in helping me test this language server on Emacs at some point (low priority)?