MM-60331 - Scheduled post telemetry (#29132)

* Added scheduled posts telemetry

* Tracking scheudled post creation via webapp to filter by platform

* Fixed keys

* Lint fix

server/platform/services/telemetry/telemetry.go

@@ -107,6 +107,7 @@ const (
 	TrackGroupsFeature         TrackFeature = "custom_groups"
 	TrackReadOnlyFeature       TrackFeature = "read_only_channels"
 	TrackSharedChannelsFeature TrackFeature = "shared_channels"
+	TrackScheduledPosts        TrackFeature = "scheduled_posts"
 )
 
 const (
@@ -114,6 +115,7 @@ const (
 	TrackPropertyGroup      = "group_id"
 	TrackPropertyChannel    = "channel_id"
 	TrackPropertyPostAuthor = "post_owner_id"
+	TrackPropertyUserAgent  = "user_agent"
 )
 
 type ServerIface interface {