Issue #23459 Issue #23937 Support external pre-auths with no card_id.

Uses:
https://github.com/xtuple/qt-client/pull/381
It looks like:

<prerequisite type = "query" name = "Checking for duplicate Characteristic names" >
  <query>SELECT NOT EXISTS(SELECT COUNT(*), char_name FROM "char" GROUP BY char_name HAVING COUNT(*) > 1);</query>
  <message>The char table (characteristics) has duplicate values in the char_name column. Please check Products > Setup > Characteristics and remove or change these duplicates before upgrading.</message>
  </prerequisite>

Just needs to be before the initscripts section or any of the file elements. The query needs to return TRUE to continue successfully. I looked quickly and I didn't see an easy way to validate multiple-column unique constraints however...