Add Emoji support

[AWolf81]

Issue #245

Description
I've added remark-emoji.

An example markdown is:

Hey there :+1:

I :heart: Emojis

Which renders like this:

Tested

• Windows 10 64bit Desktop (working)
• Linux Ubuntu (test outstanding)
• MacOS (I need help here - I don't have a Mac here)
• Dev mobile (working)
• WebApp (working)
• Emojis from https://markdown-it.github.io/ rendering (except shortcodes)

Notes

• Emoticons like :-) are not supported. I'll check if remark-emoticon could be used. OK, I've checked this and remark-emoticon is not what I want to use - adding own images is too complicated. retext-emoji is better than remark-emoji and also supporting short-codes like :-) (see demo). But I couldn't get remark2retext to work. I think I'll write a remark-plugin that is using emoticon for shortcode handling. Or am I missing something?
• Emoticons will be supported with an update of remark-emoji. If the following PR is merged.

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IssueHunt Summary

Referenced issues

This pull request has been submitted to:

• #245: Emoji support

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[CLAassistant]

All committers have signed the CLA.

[ZeroX-DG]

LGTM 🎉 Thanks for this PR.

[AWolf81]

@ZeroX-DG Thanks for approving. I've updated remark-emoji. With the new version Emoticons are supported.
Like in the follwing codesandbox.

Is there a docs/help section for Boostnote.next? I'd like to check if I can add some details about the feature.

[Rokt33r]

LGTM!

[Rokt33r]

@AWolf81 I'll test this on Linux and macOS and try to merge this pr tomorrow.