Rename "BanSync" module to something else

The name "BanSync" for the cross-server ban record sharing feature has confused a handful of people on what the feature actually does. It should be renamed to something else that's short, and can get the point of the feature across to the end-user at a glance.

Note: This issue exists as a reminder/todo task for myself, but I can't stop you from replying with a suggestion

Start by locating the BanSync module and its user-facing references in the XeniaBot codebase. Review the feature's current naming and how cross-server ban record sharing is presented before proposing a short replacement. Done means a name is agreed on and the module and user-facing references consistently use it.

Written by the indexing model from the issue text.