Support Array of Objects as list and keys to search against

Currently, only an array of strings is accepted as a list. Let's allow an array of objects instead when initializing the fuzzify library.
Additinally `keys` should be passed to `search` API

```js
const list = [{"name": "Joe", "age": "20", "designation": "Frontend Engineer"},
{"name": "Alice": "age": 25, "designation": "Backend Engineer"},
{"name": "Jack", "age": 21, "designation": "Customer Success"},
{"name": "Bob", "age": 35, "designation": "Engineering Manager"}];

const keys = ["name", "age"];
const fuzzy = new Fuzzy(list);
const result = fuzzy.search(query, keys);
```