[RRFC] Parallel script execution when value is set to an array of text.

Currently a script can not be set to array. Add this to your package.json,

  "scripts": {
    "foo": [
      "echo bar",
      "echo baz"
    ]
  },

Now if you try to run it,

npm run-script foo

You'll get

npm ERR! Missing script: "foo"
npm ERR! 
npm ERR! To see a list of scripts, run:
npm ERR!   npm run

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/ecarroll/.npm/_logs/2022-07-02T19_32_38_351Z-debug-0.log

The obvious intent here is to run two scripts where neither one is concerned with the status of another. This RFC would define the behavior of script with a member set to an array to,

1. Run both scripts without regard for return codes of other scripts defined,
2. Run both scripts in parallel.

The RFC names package.json and npm run-script as the entry points; begin by tracing how scripts are read and invoked. Define and verify array-valued scripts so both commands run in parallel without one return code stopping the other, then check the behavior with npm run-script foo.