hostapd: add association frame to taxonomy data

hostapd: add association frame to taxonomy data

Extend the taxonomy subsystem to capture the complete association frame
in addition to the existing probe and association IE data.

This adds a new assoc_frame_taxonomy field to struct sta_info and exposes
it via the get_sta_ies ubus method as a base64-encoded "assoc_frame" field.

Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>