Add `NS_FORMAT_FUNCTION` qualifier to `executeQueryWithFormat` and `executeUpdateWithFormat`

These two methods, `executeQueryWithFormat` and `executeUpdateWithFormat`, take format strings and variable number of arguments. With this change, you will now receive compiler warnings if the types of your parameters don't match the format string. This gives the developer a few more hints when writing code about making sure parameters match format strings.

By the way, when doing this, I noticed (and fixed) problem in fmdb.m test code, in which the format string was expecting `long long`, but value was merely `long`.