[Feature] Standalone scripts and node processes

[Lucassifoni]

Goals

• An ergonomic way to define scripts in Elixir code, with (optional) formatting on mix format
• Building on Nodelix.Npm, allow to define and install dependencies for a script
• Run one-off scripts without configuring a nodelix profile
• Launch a long-running script in a port

I'll start with my POC ( https://github.com/alzo-archi/nodelix/tree/sigils_and_standalone_scripts ) and build upon it.

Custom sigils must be opt-in or Nodelix will fail to compile under 1.15.

For examples of that "<lang> inside elixir module" feature, see Zigler : https://hexdocs.pm/zigler/Zig.html#module-basic-nifs

[Lucassifoni]

Update on syntax highlighting (which I wanted for my own use) : it is possible to provide a tree-sitter grammar that matches custom sigils, but in the end that needs to be loaded in each user's editor.
So that's out of scope, I'll provide a tree-sitter grammar repo but won't support editor plugins, and not in the nodelix repo either.
For the sake of documentation here's an example of a non-prod-ready VSCode plugin that loads a tree-sitter grammar for ~JS sigils : https://github.com/alzo-archi/vscode-sigil-js-highlighting-sample