@typescript-eslint/tslint-eslint-plugin isn't suggested for installation when necessary

[JoshuaKGoldberg]

🐛 Bug Report

• tslint-to-eslint-config version: 0.6.0
• ESLint version: N/A
• Node version: N/A

Actual Behavior

If you run tslint-to-eslint-config on a tslint.json with unrecognized rules, you might get a message like:

...
⚡ 6 packages are required for running with ESLint. ⚡
  npm install @typescript-eslint/eslint-plugin @typescript-eslint/parser eslint eslint-plugin-import eslint-plugin-jsdoc eslint-plugin-prefer-arrow --save-dev

Expected Behavior

It should be 7 packages, with the addition of @typescript-eslint/tslint-eslint-plugin.

Reproduction

https://github.com/KingDarBoja/sample-tslint-to-eslint-comment

This was introduced in #405. 😁