Disallow using `1` as the `depth` argument of `Array#flat()`

💼 This rule is enabled in the ✅ recommended config.

🔧 This rule is automatically fixable by the --fix CLI option.

Passing 1 as the depth argument to Array#flat(depth) is unnecessary.

Examples

// ❌
foo.flat(1);

// ✅
foo.flat();

// ❌
foo?.flat(1);

// ✅
foo?.flat();