Perform partial initial scan with  reduced channels

This commit adds an optional feature to perform a fast initial scanning
with a reduced number of channels from the connected channel history.
The maximum number of channels in the reduced scan, and the maximum age
for the history are configurable.

Bug: 141893780
Test: atest com.android.server.wifi
Change-Id: I93081524b9fee6db13cfc989533cf38f6d270874
5 files changed