Implement stats.getBroadcastStats

[aykutalparslan]

Get channel statistics

stats.broadcastStats#bdf78394 period:StatsDateRangeDays followers:StatsAbsValueAndPrev views_per_post:StatsAbsValueAndPrev shares_per_post:StatsAbsValueAndPrev enabled_notifications:StatsPercentValue growth_graph:StatsGraph followers_graph:StatsGraph mute_graph:StatsGraph top_hours_graph:StatsGraph interactions_graph:StatsGraph iv_interactions_graph:StatsGraph views_by_source_graph:StatsGraph new_followers_by_source_graph:StatsGraph languages_graph:StatsGraph recent_message_interactions:Vector<MessageInteractionCounters> = stats.BroadcastStats; ---functions--- stats.getBroadcastStats#ab42441a flags:# dark:flags.0?true channel:InputChannel = stats.BroadcastStats;