MM-8853: Adding MANAGE_EMOJIS and MANAGE_OTHERS_EMOJIS permissions (#8860)

* MM-8853: Adding MANAGE_EMOJIS and MANAGE_OTHERS_EMOJIS permissions

* MM-8853: Removing unnecesary emoji enterprise feature

* Create emojis migration

* Adding MANAGE_EMOJIS and MANAGE_OTHERS_EMOJIS always to system admins

* Simplifing permissions checks

* Revert "Simplifing permissions checks"

This reverts commit e2cafc1905fc9e20125dd9a1552d2d0c7340ae59.

app/permissions.go

@@ -43,6 +43,7 @@ func (a *App) ResetPermissionsSystem() *model.AppError {
 
 	// Now that the permissions system has been reset, re-run the migration to reinitialise it.
 	a.DoAdvancedPermissionsMigration()
+	a.DoEmojisPermissionsMigration()
 
 	return nil
 }