PLT-3143 Added serverside code for custom Emoji (#3311)

* Added model objects for emoji

* Added database tables for emoji

* Added settings for custom emoji

* Added serverside APIs and unit tests for custom emoji

* Added additional validation to catch duplicate emoji names earlier on

* Added additional validation to prevent users from adding emoji as another user

model/config.go

@@ -34,6 +34,9 @@ const (
 	DIRECT_MESSAGE_TEAM = "team"
 
 	FAKE_SETTING = "********************************"
+
+	RESTRICT_EMOJI_CREATION_ALL   = "all"
+	RESTRICT_EMOJI_CREATION_ADMIN = "system_admin"
 )
 
 // should match the values in webapp/i18n/i18n.jsx
@@ -70,6 +73,8 @@ type ServiceSettings struct {
 	WebsocketSecurePort               *int
 	WebsocketPort                     *int
 	WebserverMode                     *string
+	EnableCustomEmoji                 *bool
+	RestrictCustomEmojiCreation       *string
 }
 
 type SSOSettings struct {
@@ -565,6 +570,16 @@ func (o *Config) SetDefaults() {
 		*o.ServiceSettings.WebserverMode = "regular"
 	}
 
+	if o.ServiceSettings.EnableCustomEmoji == nil {
+		o.ServiceSettings.EnableCustomEmoji = new(bool)
+		*o.ServiceSettings.EnableCustomEmoji = true
+	}
+
+	if o.ServiceSettings.RestrictCustomEmojiCreation == nil {
+		o.ServiceSettings.RestrictCustomEmojiCreation = new(string)
+		*o.ServiceSettings.RestrictCustomEmojiCreation = RESTRICT_EMOJI_CREATION_ALL
+	}
+
 	if o.ComplianceSettings.Enable == nil {
 		o.ComplianceSettings.Enable = new(bool)
 		*o.ComplianceSettings.Enable = false