wifi(implementation): Move set/getMacaddress to a util class

This is just a refactor to move the setMacAddress & getFactoryMacAddress
methods to a util class within the HAL. This can be then reused in AP
iface for mac randomization of SoftAp.

This also fixes a bug in the existing setMacAddress() method, the
current method always sets wlan0 up/down. STA interface could be wlan1
on some devices.

Bug: 78353419
Test: ./hardware/interfaces/wifi/1.3/default/tests/runtests.sh
Test: Manually verified STA MAC randomization still works.
Change-Id: I0bb8154f7e6dcae37c977454423c8c299762260e