Adding an option to return SQL_INT8 as a number or as a string

[true-alex]

In versions prior to 3.0.0, values of type SQL_INT8 were returned as strings, in some cases it was convenient, for example, when passing returned values to a web browser, since in JavaScript the integer type is 53 bits. The pg_int8_as_string option, when true, returns the old behavior and returns 64-bit integer values as strings (default is false).