allow ignoring devDependencies when running task from package.json

[scarf005]

https://github.com/scarf005/vfile/blob/67e5cbcab3c9c1b1a47cb796f9bba3100e5c7aab/package.json#L56-L70

  "dependencies": {
    "@types/unist": "^3.0.0",
    "unist-util-stringify-position": "^4.0.0",
    "vfile-message": "^4.0.0"
  },
  "devDependencies": {
    "@types/node": "^20.0.0",
    "c8": "^8.0.0",
    "prettier": "^3.0.0",
    "remark-cli": "^11.0.0",
    "remark-preset-wooorm": "^9.0.0",
    "type-coverage": "^2.0.0",
    "typescript": "^5.0.0",
    "xo": "^0.56.0"
  },

in this library, only dependencies is required to run. however,

deno eval 'import "lib/index.js"'

will attempt to download the entire content of devDependencies. while the workaround is to erase devDependencies before running then restoring, it's a bit manual. a flag like --ignore-devdependencies would be helpful.