Add ESLint config to suppress no-unused-vars rule for variables with leading underscore

[DylanSp]

argsIgnorePattern - https://eslint.org/docs/latest/rules/no-unused-vars#argsignorepattern - should work fine.

destructuredArrayIgnorePattern - https://eslint.org/docs/latest/rules/no-unused-vars#destructuredarrayignorepattern

• Had issues on laptop (Windows + WSL) - still reported a warning from the eslint no-unused-vars rule directly, not the @typescript-eslint wrapper (which is what warned for arguments)
• Test case (should not warn for _b if rule is properly suppressed):

const [a, _b, c] = ["a", "b", "c"];
console.log(a+c);

• @typescript-eslint wrapper docs
• @typescript-eslint should turn off regular eslint rule, per docs and source code
• Might be something with ESLint plugin and/or VS Code general configuration?

[DylanSp]

Guide of what to add:

rules: {
    // Place to specify ESLint rules. Can be used to overwrite rules specified from the extended configs
    // e.g. "@typescript-eslint/explicit-function-return-type": "off",
    "prettier/prettier": "warn",
    "@typescript-eslint/no-unused-vars": [
      "warn",
      {
        argsIgnorePattern: "^_",
        destructuredArrayIgnorePattern: "^_",
      },
    ],
  },