Calls to postgres polymorphic functions fail

[ashertarno]

The following call:

ReactiveRXGenericQueryExecutor executor =...
executor.query(dslCtx -> dslCtx.selectFrom(DSL.generateSeries(3, 10)))...

will return error io.vertx.pgclient.PgException: function generate_series(unknown, unknown) is not unique

This happens because while all of the queries are turned into prepared statements by AbstractReactiveQueryExecutor.toPreparedQuery() using ParamType.NAMED, such usage isn't allowed in cases of postgres polymorphic functions like generate_series. The usage for such functions in prepared statements is possible only with explicitly cast parameters, e.g. generate_series($1::int,$2::int), while they work without any issues in regular statements.