sqlite: use `BLOB' column type instead of `VARBINARY'

sqlite: use `BLOB' column type instead of `VARBINARY'

`VARBINARY' isn't actually a documented type for SQLite but
rather the result of MySQL infecting my mind decades ago.
`BLOB' gives it the proper affinity and probably makes it easier
for 3rd-party and one-off scripts to deal with such columns and
should also make things more familiar to existing users.
Surprisingly, this appears to have no functional change with
forward or backwards compatibility since we ->bind_param binary
data with SQL_BLOB on INSERTs anyways to prevent the flexible
typing of SQLite from trying to guess types for us.