Test setting of a replay-window to non-default (default is 128) value 0 and 256 for ikev2

Note that ESN is disabled when replay-window=0 because  RFC 4304 (and Linux XFRM) say so:

    Note: If a receiver chooses to not enable anti-replay for an SA, then
    the receiver SHOULD NOT negotiate ESN in an SA management protocol.
    Use of ESN creates a need for the receiver to manage the anti-replay
    window (in order to determine the correct value for the high-order
    bits of the ESN, which are employed in the ICV computation), which is
    generally contrary to the notion of disabling anti-replay for an SA.

