Make connection command-line parameters optional

[captaincoordinates]

It is not currently possible to connect to RDS Proxy using pypgstac due to its use of command-line parameters. Connection attempts fail with

connection to server at "...rds.amazonaws.com" (IP), port 5432 failed: FATAL: Feature not supported: RDS Proxy currently doesn’t support command-line options.

I've also seen a similar error when working with pgbouncer.

I had to override the PgstacDB class with the following to make this work

class _ProxyCompatiblePgstacDB(PgstacDB):
    def get_pool(self) -> ConnectionPool:
        if self.pool is None:  # type: ignore
            self.pool = ConnectionPool(
                conninfo=self.dsn,
                min_size=pypgstac_settings.db_min_conn_size,
                max_size=pypgstac_settings.db_max_conn_size,
                max_waiting=pypgstac_settings.db_max_queries,
                max_idle=pypgstac_settings.db_max_idle,
                num_workers=pypgstac_settings.db_num_workers,
            )
        return self.pool

    def connect(self) -> Connection:
        connection = super().connect()
        connection.execute("set search_path = pgstac,public")
        return connection

Perhaps there can be a configuration option, or a variation on the above, to avoid always attempting to send command-line options.