add GetChannelsForTeamForUser to plugin api (#9646)

plugin/api.go

@@ -128,6 +128,9 @@ type API interface {
 	// GetChannelByNameForTeamName gets a channel by its name, given a team name.
 	GetChannelByNameForTeamName(teamName, channelName string, includeDeleted bool) (*model.Channel, *model.AppError)
 
+	// GetChannelsForTeamForUser gets a list of channels for given user ID in given team ID.
+	GetChannelsForTeamForUser(teamId, userId string, includeDeleted bool) (*model.ChannelList, *model.AppError)
+
 	// GetDirectChannel gets a direct message channel.
 	GetDirectChannel(userId1, userId2 string) (*model.Channel, *model.AppError)