Optional raw identifiers

Steps to reproduce

esprima.parse('var \u00e0;')

Expected output

{
  "type": "Program",
  "body": [
    {
      "type": "ExpressionStatement",
      "expression": {
        "type": "Identifier",
        "name": "\u00e0"
      }
    }
  ],
  "sourceType": "script"
}

Actual output

{
  "type": "Program",
  "body": [
    {
      "type": "ExpressionStatement",
      "expression": {
        "type": "Identifier",
        "name": "à"
      }
    }
  ],
  "sourceType": "script"
}

I didn't expect identifiers in unicode format to be transformed, which is okay of course, I would like to ask if an option to keep Identifiers and function names unencoded can be added.

Thanks!

Start by running the reported esprima.parse('var à;') reproduction and trace how identifier names are represented in the parser output. Define the option's behavior for identifiers and function names, then add coverage showing raw spelling is preserved when enabled without changing the default output.