XYZ-35: Added Support for GlobalRelay Compliance Export Format

* Added username to ChannelMemberHistory struct in anticipation of supporting GlobalRelay in Compliance Export
* Removed translation from debug output - this makes it complicated to use utils functions from tests in the enterprise repo
* Added an advanced email function that allows for greater control over message details. Updated MessageExport config to support GlobalRelay. Added attachment support to InBucket unit tests
* Moving templates in from enterprise to solve test issues
* Added export format to diagnostics
* Changed email attachment code to use FileBackend so that S3 storage is properly supported

app/diagnostics.go

@@ -501,6 +501,7 @@ func (a *App) trackConfig() {
 
 	a.SendDiagnostic(TRACK_CONFIG_MESSAGE_EXPORT, map[string]interface{}{
 		"enable_message_export":         *cfg.MessageExportSettings.EnableExport,
+		"export_format":                 *cfg.MessageExportSettings.ExportFormat,
 		"daily_run_time":                *cfg.MessageExportSettings.DailyRunTime,
 		"default_export_from_timestamp": *cfg.MessageExportSettings.ExportFromTimestamp,
 		"batch_size":                    *cfg.MessageExportSettings.BatchSize,