Add if_exists param to aupsert

[Aragonski97]

In https://github.com/ThibTrip/pangres/wiki/Aupsert we are asked to create a table before upserting.
Would it be an inconvenience to add if_exists param to aupsert function similar to the one used in df.to_sql from pandas library?

Edit:
This actually might be it. Although this function is tied to PandasSpecialEngine which needs prepared df in order to instantiate.

def table_exists(self, connection: Union[Connection, None] = None) -> bool:
        """
        Returns True if the table defined in given instance
        of PandasSpecialEngine exists else returns False.
        """
        con = self.connection if connection is None else connection
        insp = sa.inspect(con)
        if _sqla_gt14():
            return insp.has_table(schema=self.schema, table_name=self.table.name)  # type: ignore
        else:
            # this is not particularly efficient but AFAIK it's the best we can do at connection level
            return self.table.name in insp.get_table_names(schema=self.schema)  # type: ignore