turn off defense in ffi to allow modifying table sqlite_master

[veronikalaskova]

During an upgrade script I alter the original SQL and add foreign keys to the table and encounter a 'table sqlite_master may not be modified' error.
There was already a known issue (#525) that talked about this and had the workaround mentioned.

This problem was re-discovered when writing unit tests (using sqflite_common_ffi) for the upgrade scripts. Same error popped up again as FFI does not currently have a workaround for this.

This PR turns off the SQLITE_DBCONFIG_DEFENSIVE if the SQL command is to set the db_config_defensive_off.

[alextekartik]

Great ! Thanks for diving and finding a similar solution. I'll merge and will try to setup a unit test. I might tweak a little (such as not executing the pragma at all (although it does not hurt, it is just a waste of time.

[alextekartik]

Published in sqflite_common_ffi 2.3.0+4

[alextekartik]

Thanks !