MM-15021: Adding new builtin system schema for Guests (#10601)

* MM-15021: Adding new builtin system schema for Guests

* Fixing tests

* Setting properly the permissions

* Adding guests to sampledata

* Restrict more roles updates in the app layer for guests

* Adding comment to explain that permissions migration must go at the end

* Setting the default guest role for custom scheme during migration

* Fixing import and export

* Creating scheme guest roles on migration

* Fixing tests

* Fixing tests

* Fixing tests

app/export_converters.go

@@ -91,6 +91,9 @@ func ImportUserTeamDataFromTeamMember(member *model.TeamMemberForExport) *UserTe
 	if member.SchemeUser {
 		rolesList = append(rolesList, model.TEAM_USER_ROLE_ID)
 	}
+	if member.SchemeGuest {
+		rolesList = append(rolesList, model.TEAM_GUEST_ROLE_ID)
+	}
 	roles := strings.Join(rolesList, " ")
 	return &UserTeamImportData{
 		Name:  &member.TeamName,
@@ -106,6 +109,9 @@ func ImportUserChannelDataFromChannelMemberAndPreferences(member *model.ChannelM
 	if member.SchemeUser {
 		rolesList = append(rolesList, model.CHANNEL_USER_ROLE_ID)
 	}
+	if member.SchemeGuest {
+		rolesList = append(rolesList, model.CHANNEL_GUEST_ROLE_ID)
+	}
 	props := member.NotifyProps
 	notifyProps := UserChannelNotifyPropsImportData{}