PLT-1378 Initial version of emoji reactions (#4520)

* Refactored emoji.json to support multiple aliases and emoji categories

* Added custom category to emoji.jsx and stabilized all fields

* Removed conflicting aliases for :mattermost: and :ca:

* fixup after store changes

* Added emoji reactions

* Removed reactions for an emoji when that emoji is deleted

* Fixed incorrect test case

* Renamed ReactionList to ReactionListView

* Fixed 👍 and 👎 not showing up as possible reactions

* Removed text emoticons from emoji reaction autocomplete

* Changed emoji reactions to be sorted by the order that they were first created

* Set a maximum number of listeners for the ReactionStore

* Removed unused code from Textbox component

* Fixed reaction permissions

* Changed error code when trying to modify reactions for another user

* Fixed merge conflicts

* Properly applied theme colours to reactions

* Fixed ESLint and gofmt errors

* Fixed ReactionListContainer to properly update when its post prop changes

* Removed unnecessary escape characters from reaction regexes

* Shared reaction message pattern between CreatePost and CreateComment

* Removed an unnecessary select query when saving a reaction

* Changed reactions route to be under /reactions

* Fixed copyright dates on newly added files

* Removed debug code that prevented all unit tests from being ran

* Cleaned up unnecessary code for reactions

* Renamed ReactionStore.List to ReactionStore.GetForPost

tests/test-emoticons1.md

@@ -1,7 +1,7 @@
 # Emoticon Testing  
 Verify that all emoticons render. 
 
-:mm: :mattermost:
+:mattermost:
 
 ### Emoticon - Punctuation  
 

tests/test-emoticons3.md

@@ -1,3 +1,3 @@
 ### Emoticons - Places     
 
-:house: :house_with_garden: :school: :office: :post_office: :hospital: :bank: :convenience_store: :love_hotel: :hotel: :wedding: :church: :department_store: :european_post_office: :city_sunrise: :city_sunset: :japanese_castle: :european_castle: :tent: :factory: :tokyo_tower: :japan: :mount_fuji: :sunrise_over_mountains: :sunrise: :stars: :statue_of_liberty: :bridge_at_night: :carousel_horse: :rainbow: :ferris_wheel: :fountain: :roller_coaster: :ship: :speedboat: :boat: :sailboat: :rowboat: :anchor: :rocket: :airplane: :helicopter: :steam_locomotive: :tram: :mountain_railway: :bike: :aerial_tramway: :suspension_railway: :mountain_cableway: :tractor: :blue_car: :oncoming_automobile: :car: :red_car: :taxi: :oncoming_taxi: :articulated_lorry: :bus: :oncoming_bus: :rotating_light: :police_car: :oncoming_police_car: :fire_engine: :ambulance: :minibus: :truck: :train: :station: :train2: :bullettrain_front: :bullettrain_side: :light_rail: :monorail: :railway_car: :trolleybus: :ticket: :fuelpump: :vertical_traffic_light: :traffic_light: :warning: :construction: :beginner: :atm: :slot_machine: :busstop: :barber: :hotsprings: :checkered_flag: :crossed_flags: :izakaya_lantern: :moyai: :circus_tent: :performing_arts: :round_pushpin: :triangular_flag_on_post: :jp: :kr: :cn: :us: :fr: :es: :it: :ru: :gb: :uk: :de: :ca: :eh: :pk: :za:  
+:house: :house_with_garden: :school: :office: :post_office: :hospital: :bank: :convenience_store: :love_hotel: :hotel: :wedding: :church: :department_store: :european_post_office: :city_sunrise: :city_sunset: :japanese_castle: :european_castle: :tent: :factory: :tokyo_tower: :japan: :mount_fuji: :sunrise_over_mountains: :sunrise: :stars: :statue_of_liberty: :bridge_at_night: :carousel_horse: :rainbow: :ferris_wheel: :fountain: :roller_coaster: :ship: :speedboat: :boat: :sailboat: :rowboat: :anchor: :rocket: :airplane: :helicopter: :steam_locomotive: :tram: :mountain_railway: :bike: :aerial_tramway: :suspension_railway: :mountain_cableway: :tractor: :blue_car: :oncoming_automobile: :car: :red_car: :taxi: :oncoming_taxi: :articulated_lorry: :bus: :oncoming_bus: :rotating_light: :police_car: :oncoming_police_car: :fire_engine: :ambulance: :minibus: :truck: :train: :station: :train2: :bullettrain_front: :bullettrain_side: :light_rail: :monorail: :railway_car: :trolleybus: :ticket: :fuelpump: :vertical_traffic_light: :traffic_light: :warning: :construction: :beginner: :atm: :slot_machine: :busstop: :barber: :hotsprings: :checkered_flag: :crossed_flags: :izakaya_lantern: :moyai: :circus_tent: :performing_arts: :round_pushpin: :triangular_flag_on_post: :jp: :kr: :cn: :us: :fr: :es: :it: :ru: :gb: :uk: :de: :ca: :pk: :za: