Add ability to disable categories

[bkwhite]

It would be very helpful if categories could be disabled via component props

[arronhunt]

I'm thinking through the best pattern to achieve something like this. Instead of disabling certain categories I feel its more intuitive to whitelist them. We could have an API like this

import EmojiSelector, { Categories } from "react-native-emoji-selector";

const { flags, sports, food } = Categories;

<EmojiSelector
  onEmojiSelected={handleEmoji}
  categoriesEnabled={[
    flags, sports, food
  ]}
/>

[bkwhite]

I like that approach, it also aligns with our use case well.

[arronhunt]

This will be included in v1.0.0