PLT-7503: Create Message Export Scheduled Task and CLI Command (#7612)

* Created message export scheduled task

* Added CLI command to immediately kick off an export job

* Added email addresses for users joining and leaving the channel to the export

* Added support for both MySQL and PostgreSQL

* Fixing gofmt error

* Added a new ChannelMemberHistory store and associated tests

* Updating the ChannelMemberHistory channel as users create/join/leave channels

* Added user email to the message export object so it can be included in the actiance export xml

* Don't fail to log a leave event if a corresponding join event wasn't logged

* Adding copyright notices

* Adding message export settings to daily diagnostics report

* Added System Console integration for message export

* Cleaned up TODOs

* Made batch size configurable

* Added export from timestamp to CLI command

* Made ChannelMemberHistory table updates best effort

* Added a context-based timeout option to the message export CLI

* Minor PR updates/improvements

* Removed unnecessary fields from MessageExport object to reduce query overhead

* Removed JSON functions from the message export query in an effort to optimize performance

* Changed the way that channel member history queries and purges work to better account for edge cases

* Fixing a test I missed with the last refactor

* Added file copy functionality to file backend, improved config validation, added default config values

* Fixed file copy tests

* More concise use of the testing libraries

* Fixed context leak error

* Changed default export path to correctly place an 'export' directory under the 'data' directory

* Can't delete records from a read replica

* Fixed copy file tests

* Start job workers when license is applied, if configured to do so

* Suggestions from the PR

* Moar unit tests

* Fixed test imports

app/diagnostics.go

@@ -44,6 +44,7 @@ const (
 	TRACK_CONFIG_ELASTICSEARCH  = "config_elasticsearch"
 	TRACK_CONFIG_PLUGIN         = "config_plugin"
 	TRACK_CONFIG_DATA_RETENTION = "config_data_retention"
+	TRACK_CONFIG_MESSAGE_EXPORT = "config_message_export"
 
 	TRACK_ACTIVITY = "activity"
 	TRACK_LICENSE  = "license"
@@ -470,6 +471,13 @@ func (a *App) trackConfig() {
 		"file_retention_days":     *cfg.DataRetentionSettings.FileRetentionDays,
 		"deletion_job_start_time": *cfg.DataRetentionSettings.DeletionJobStartTime,
 	})
+
+	SendDiagnostic(TRACK_CONFIG_MESSAGE_EXPORT, map[string]interface{}{
+		"enable_message_export":         *cfg.MessageExportSettings.EnableExport,
+		"daily_run_time":                *cfg.MessageExportSettings.DailyRunTime,
+		"default_export_from_timestamp": *cfg.MessageExportSettings.ExportFromTimestamp,
+		"batch_size":                    *cfg.MessageExportSettings.BatchSize,
+	})
 }
 
 func trackLicense() {