wifi: Add Support for Multi-Link Layer stats in shim layer

With MLO, WiFi 7 supports establishing multiple links between the
Station and Access Point. Each of the link has its own stats.

To maintain backward compatibility, if multi link stats is not supported
by vendor, always fallback to single link layer stats.

Bug: 246988155
Test: hardware/interfaces/wifi/aidl/default/tests/runtests.sh
Change-Id: Iede8ce771f0e58975222808b1870e5e2e179384c