Add an option to fetch password from file for CONNECT operator

[pavel-zotov]

It would be nice to be able to run script with:

CONNECT 'some_db_1' as user foo fetch_password '/opt/firebird/foo.password';
... do something with DB_1 as user foo ...
commit;
CONNECT 'some_db_1' as user bar fetch_password '/opt/firebird/bar.password';
... do something with DB_1 as user bar ...
commit;