Ability to insert emojis into status and comments

First pass of an emoji component can be found below.

• Comments context -> https://www.sketch.com/s/5c6ca256-987d-4698-a4aa-dbaf0b3e1c2e/v/Jv9OQ7/a/xrR7y4J/r/oLzJP0
• Composer context -> https://www.sketch.com/s/5c6ca256-987d-4698-a4aa-dbaf0b3e1c2e/v/oLzJP0/a/R1RWLK8/r/y5a1Zy

Notes

• The emoji component is a requirement only for web (not a requirement for mobile)
• Users can access recently used emojis. Where there are no recently used emojis, this section will not display.
• Emojis are arranged by the following categories: Recently User, Smileys & People, Animals & Nature, Food & Drink, Travel & Places, Activities, Objects, Symbols, Flags
• When activated, the search input should be focused.
• The menu position should adapt appropriately, depending on its position within the viewport. If there's little space under the emoji action, the menu should appear above. Where there's little space on RHS, the menu should be shirted towards the lift. I believe the channel card popover users Popper JS, would could be useful here -> https://popper.js.org/
• It's probably not necessary to display the emoji icon on responsive mobile. Perhaps it could be included as an option within the ellipsis menu. -> https://www.sketch.com/s/5c6ca256-987d-4698-a4aa-dbaf0b3e1c2e/v/oLzJP0/a/pam7AxJ

https://github.com/twitter/twemoji