Improvement CORE-3881: Extend the error reported for index/constraint violations to include the problematic key value.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@59016 65644016-39b1-43b1-bf79-96bc8fe82c15
Misc.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@59017 65644016-39b1-43b1-bf79-96bc8fe82c15