Provide ability to see in the trace log events related to missing security context

Following attempt of attach:
```set ISC_USER=
set ISC_PASSWORD=
echo quit; | C:\path\to\FB4x\isql.exe localhost:employee -q
Statement failed, SQLSTATE = 28000
Missing security context for employee
```
-- will not be logged in the trace.
It will be good to see such attempts.