Add a config setting in the UI for range

The last submitted patch, 2: message_subscribe-range_config_setting-3300223-2.patch, failed testing. View results →
- codesniffer_fixes.patch Interdiff of automated coding standards fixes only.

I added the range value to the schema, and provided a default value.

Adds message_subscribe_update_8121 function for new setting.

Update config test with new value.

Automatically closed - issue fixed for 2 weeks with no activity.