wifi-scripts: add support for RSN overide and use it for improved WPA3 compat

wifi-scripts: add support for RSN overide and use it for improved WPA3 compat

Override via RSNE is a relatively new feature, which can be used to enable
WPA3 features in a way that is invisible to older clients.
Use it by default to mask the GCMP-256 cipher from older clients, since
there are compatibility issues with existing devices.

Signed-off-by: Felix Fietkau <[email protected]>