Support LINE text message with emoji

[hearsilent]

@boybundit Please review this 🙏

[boybundit]

@hearsilent I don't yet see any benefit adding emojis as arguments because ones can construct the json message structure they want and just pass the message object. Perhaps we can help populate the index parameter?

I think it would be better if we offer easier way to send emoji. For example:

// Users define frequently used emojis in our chosen format e.g. {{emoji/productId/emojiId}}
const EMOJI_HEART_EYES = '{{emoji/5ac1bfd5040ab15980c9b435/001}}';
const EMOJI_CLOSED_EYES_SMILE = '{{emoji/5ac1bfd5040ab15980c9b435/001}}';

// Users insert emoji into plain text reply
event.reply(`${EMOJI_HEART_EYES} LINE emoji ${EMOJI_CLOSED_EYES_SMILE}`);

And linebot will convert the text into correct text object with emojis array.

{
    "type": "text",
    "text": "$ LINE emoji $",
    "emojis": [
      {
        "index": 0,
        "productId": "5ac1bfd5040ab15980c9b435",
        "emojiId": "001"
      },
      {
        "index": 13,
        "productId": "5ac1bfd5040ab15980c9b435",
        "emojiId": "002"
      }
    ]
}

[hearsilent]

@boybundit You're right! The origin code can put full object to support emojis, this PR is unnecessary.

I'll try to support this

event.reply(`${EMOJI_HEART_EYES} LINE emoji ${EMOJI_CLOSED_EYES_SMILE}`);

If I've time 😅

Thx for suggestions!