[Feature] Add filterFunctions prop to enable emojis filtering

[darekg11]

Relate to any issue?

https://github.com/sskhandek/react-native-emoji-input/issues/5
It is a temporary workaround that would allow user of this library to avoid missing emojis being render as X

Breaking change?

Nope, by default all emojis will be rendered as before.

What this PR does?

Adds new filterFunctions prop allowing user to pass an array of functions used to filter emojis list before rendering it

Example of usage:

    filterFunctionByUnicode = emoji => {
        return emoji.lib.added_in === "6.0" || emoji.lib.added_in === "6.1"
    }

    <EmojiInput
        onEmojiSelected={this.handleEmojiSelected}
        ref={emojiInput => this._emojiInput = emojiInput}
        resetSearch={this.state.reset}
        loggingFunction={this.verboseLoggingFunction.bind(this)}
        verboseLoggingFunction={true}
        filterFunctions={[this.filterFunctionByUnicode]}
    />

Change Preview:

Before on my Huawei P8Lite running Android 6.0:

After enabling only 6.0 Unicode:

[darekg11]

@rijn Let me know what You think : )

[darekg11]

No problem 👌

[sskhandek]

Thank you for all the work here @rijn and @darekg11

[darekg11]

No problem, glad to help.