feat(node): add --experimental-loader CLI flag for Node.js compat
Adds proper support for Node.js's --experimental-loader flag. When a
child process is spawned with --experimental-loader, the flag is now
passed through as a native Deno CLI flag instead of being converted
to a fragile --import data URL.
The implementation:
- Adds --experimental-loader as a hidden CLI flag (with --loader alias)
- Before the main module runs, eagerly imports each loader module and
registers its resolve/load hooks via the existing async hook system
- Handles top-level errors in loader modules with Node.js-compatible
output (using util.inspect for objects/functions)
- Updates node_shim translation to pass the flag through directly
