Discuss and implement solution for DBMS specific detection/enumeration limitations:

• Firebird needs a proper string unescaping - but we don't know (in time of testing) the version of the backend firebird, hence we don't know if the unescaping meant for the >=2.1 will work on it.
• IBM DB2 needs the UNION payload with exact datatypes to detect/exploit UNION query SQLi - NULL does not work, one number for each column neither if the data type is varchar, etc.