[catalogue] Fixed #845 An RdbmsCatalogue iterator should return its underlying database connection when the last row has been fetched

Adds support for byte array columns in the DB. Implementation done for
SQLite, the others are placeholders.

Adds support for byte array columns in the DB. Implementation done for
SQLite, the others are placeholders.

Set default value of autocommitMode parameter of executeQuery() and executeNonQuery() to AutocommitMode::AUTOCOMMIT_ON

Moved autocommitMode parameter from Stmt constructor to Stmt::executeQuery() and Stmt::executeNonQuery()

Done

This commit also enforces the interdiction of empty strings being
bound as string database parameters.  Either a non-empty string is
bound or no value at all is bound (nullopt).