Add testing functionality for resetting PN/IPN for configured keys

Add testing functionality for resetting PN/IPN for configured keys

This can be used to test replay protection. The "RESET_PN" command in
wpa_supplicant and "RESET_PN <addr>" command in hostapd resets the local
counters to zero for the last configured key. For hostapd, the address
parameter specifies which STA this operation is for or selects GTK
("ff:ff:ff:ff:ff:ff") or IGTK ("ff:ff:ff:ff:ff:ff IGTK").

This functionality is for testing purposes and included only in builds
with CONFIG_TESTING_OPTIONS=y.

Signed-off-by: Jouni Malinen <j@w1.fi>