Lodash set

Implement set(object, path, value), in the spirit of Lodash's _.set: write a value at a nested path, creating the missing parts. It modifies object and returns it.

• path is a string like "a.b.c", "a[0].b" or "a[0][1]", or an array of keys.
• Missing intermediate containers are created: an array when the next key is a non-negative integer ("0", "12"), otherwise a plain object.
• An existing intermediate value that is an object or array is kept. If an intermediate value exists but is not an object (a number, string, null...), replace it with a new container.
• Setting an existing path overwrites the value.
• If any key in the path is "__proto__", do nothing and return object unchanged, so the call cannot pollute Object.prototype.

The path is non-empty and keys do not contain dots or brackets.