Bug Fix: Ensure category ids are not dropped after emojisToShowFilter call

[mwadden]

Providing the emojisToShowFilter function to the component was causing the following React warning:

ERROR: 'Warning: Each child in an array or iterator should have a unique "key" prop.

Check the render method of Anchors. See https://fb.me/react-warning-keys for more information.
in span (created by Anchors)
in Anchors (created by Picker)
in div (created by Picker)
in div (created by Picker)
in Picker'

The cause was that the new category that's created with the filtered results didn't have its id value specified (only its name and emojis attributes).

This PR simply adds the id field back into the category. I've added an additional test to check for it as well.

Thanks for this great component!

[EtienneLem]

Nicely spotted! Thank you 🤘